Search

Summary Artificial E. coli endotoxin mastitis was induced in one gland (homolateral gland) of lactating goats. Mammary blood flow (MBF) was always measured in the heterolateral gland and sometimes in the homolateral gland as well, using the electromagnetic flow technique. In the homolateral gland two conspicuous MBF peaks, separated by an intervening period of low flow, swelling and pain and gross alterations in milk composition were observed. The clinical aspect, chloride concentration and total cell count in milk were not significantly altered in the heterolateral gland, but 3 types of responses could be distinguished in its MBF. In type I (56 %) there was only one MBF peak, which coincided in time with MBF peak II of the homolateral side and which remained unaffected by severing the anastomoses between the two glands. In type II (10 %), the heterolateral MBF showed 2 distinctly separated peaks which coincided with MBF peaks I and II of the homolateral gland. MBF peak I disappeared after suturing the anastomoses between the two udder halves. In type III (33 %) no heterolateral peaks were present, but in most cases a fall of MBF, coinciding with the intervening period of low flow at the homolateral side, was observed. It is concluded that during experimental endotoxin mastitis MBF peak I is induced by locally formed mediators; the subsequent low MBF value and MBF peak II are at least partially due to systemic phenomena e. g. fever. Zusammenfassung Einflus einer experimentell induzierten Mastitis auf den Blutflus in der kontralateralen Milchdruse von laktierenden Ziegen Bei laktierenden Ziegen wurde in einer Drusenhalfte (ipsilaterale Druse) mittels E. coli-Endotoxin eine Mastitis induziert. Elektromagnetische Blutflusbestimmungen (MBF) erfolgten stets in der kontralateralen und vereinzelt auch in der ipsilateralen Druse. In der ipsilateralen Druse wurden zwei deutliche MBF-Peaks beobachtet, zwischen denen sich eine Phase mit herabgesetztem Blutflus, Schwellung, Schmerz und Auftreten grobsinnlicher Milchveranderungen befand. In der kontralateralen Druse waren die klinischen Befunde sowie der Chloridgehalt und die Zellzahl im Sekret nicht signifikant verandert. Dagegen konnten bezuglich des MBF drei Verlaufsformen unterschieden werden. Typ I (56 %) wies nur einen einzigen MBF-Peak auf, welcher mit dem MBF-Peak II der ipsilateralen Seite koinzidierte und der durch Unterbindung der Anastomosen zwischen den beiden Euterhalften nicht beeinflust wurde. Beim Typ II (10%) traten synchron mit den beiden MBF-Peaks der ipsilateralen Seite zwei deutlich voneinander getrennte MBF-Peaks auf. Peak I der kontralateralen Seite verschwand nach Unterbindung der Anastomosen zwischen den beiden Drusenhalften. Beim Typ III (33%) traten keine kontralateralen Peaks auf; in den meisten Fallen wurde jedoch ein Ruckgang des MBF, synchron mit der Zwischenphase der ipsilateralen Seite, beobachtet. Es wird angenommen, das im Verlaufe einer experimentellen Endotoxin-Mastitis eine erste MBF-Erhohung eintritt infolge von lokalen Entzundungsmediatoren. Der anschliesende erniedrigte Blutflus und der zweite MBF-Peak sind zumindest teilweise die Folge systemischer Reaktionen (z. B. Fieber). Resume Influence d'une mastite induite experimentalement sur l'irrigation sanguine dans la glande mammaire contra-laterale de chevres en lactation Une mastite a ete provoquee avec une endotoxine d'E. coli dans une mamelle (glande ipsilaterale) chez des chevres en lactation. Des determinations electromagnetiques du flux sanguin (MBF) ont ete faites constamment dans la glande contra-laterale et parfois egalement dans la glande ipsilaterale. On a observe deux pics marques MBF dans la glande ipsilaterale entre lesquels on notait une phase avec flux sanguin diminue, enflure, douleur et apparition d'alterations grossieres du lait. Les examens cliniques, le taux du chlorure et le nombre de cellules n'ont pas ete modifies de facon significative dans la glande contra-laterale. On a pu par contre differencier trois formes d'evolution de MBF. Le type I (56 %) a montre un seul pic MBF qui coincida avec le MBF-pic II du cote ipsilateral et qui ne fut pas influence par la ligature des anastomoses entre les deux moities de la mamelle. Deux pics MBF nettement separes sont apparus synchroniquement lors du type II (10%) avec les deux pics MBF du cote ipsilateral. Le pic I du cote contralateral a disparu apres une ligature des anastomoses entre les deux de la glande mammaire. Il n'y a pas eu de pics contra-lateraux avec le type III (33 %). On a cependant observe dans la plupart des cas un recul de MBF, en synchronisation avec la phase intermediaire du cote ipsilateral. On suppose qu'une premiere augmentation du flux sanguin intervient au cours d'une mastite a endotoxine experimentale a la suite de mediateurs d'inflammation locaux. Le flux sanguin abaisse qui suit et le second pic sont au moins en partie la consequence de reactions systematiques (fievre p. ex.). Resumen El influjo de una mastitis inducida experimentalmente sobre la irrigacion sanguinea en la glandula mamaria contralateral en cabras lactantes Se indujo en cabras lactantes una mastitis en una mitad de la glandula mamaria (glandula ipsilateral) mediante endotoxina de E. coli. De forma continua se llevaron a cabo valoraciones electromagneticas del flujo sanguineo (MBF) en la glandula contralateral y, a veces, en la ipsilateral. En la glandula ipsilateral se observaron dos cuspides MBF pronunciadas, entre las cuales se hallaba un periodo intermedio de flujo reducido, tumefaccion, dolor y alteraciones manifiestas en la composicion de la leche. En la glandula contralateral no estaban modificados los hallazgos clinicos ni la concentracion de cloruros ni la cantidad de celulas en la secrecion. Sin embargo, con respecto a las MBF se pudieron distinguir tres formas de respuesta. El tipo I (56 %) mostraba una sola cuspide MBF, la cual coincidia con la cuspide MBF II de la parte ipsilateral y no era influenciada por la interrupcion de las anastomosis entre las dos glandulas. En el tipo III (33%) no aparecen cuspides contralaterales; sin embargo, en la mayoria de los casos se observo un retroceso del MBF, en sincronizacion con la fase intermediaria del lado ipsilateral. Se supone que en el curso de una mastitis experimental a base de endotoxina se produce un aumento primero del flujo lacteo como consecuencia de mediadores de la inflamacion locales. El flujo sanguineo disminuido acto seguido y la cuspide MBF II son, al menos en parte, la consecuencia de reacciones sistemicas (fiebre, por ej.).

Zusammenfassung Bei wachen, laktierenden Kuhen wurden elektromagnetische Blutflusmessungen an der Euterarterie und arterielle Blutdruckmessungen in der A. carotis vorgenommen, um die adrenergischen Rezeptoren im vaskularen Bett des Euters zu untersuchen. Intravenose Injektionen von Adrenalin, Noradrenalin, Phenylephrin und Isoprenalin, vor und nach Verabreichung von den die α- oder β-Rezeptoren-blockierenden Substanzen, konnten deutlich machen, das die Blutgefase des Euters der laktierenden Kuh sowohl α- als auch β-adrenergische Rezeptoren befassen. Summary Adrenergic receptors in blood vessels in the udder of lactating cows In actively lactating cows electromagnetic blood flow measurements on the mammary arteries and arterial pressure measurements on the carotid arteries were carried out to seek for adrenergic receptors within the vascular bed of the udder. Intravenous injection of adrenalin, noradrenalin, phenylephrin and isoprenalin, before and after administration of α or β receptor-blocking substances showed clearly that the blood vessels of the udder of the lactating cow contain both α and β adrenergic receptors. Resume Recepteurs adrenergiques des vaisseaux sanguins de la mamelle chez des vaches en lactation On a effectue la mesure electromagnetique du debit sanguin dans l'artere de la glande mammaire et la pression sanguine dans l'artere carotide de vaches en lactation pour etudier les recepteurs adrenergiques du reseau vasculaire de la mamelle. Des injections intraveineuses d'adrenaline, de noradrenaline, de phenylephrine et d'isoprenaline, avant et apres l'application de substances bloquant les recepteurs α et β, ont nettement montre que les vaisseaux sanguins de la mamelle possedent aussi bien des recepteurs adrenergiques α que β. Resumen Receptores adrenergicos de los vasos mamarios en vacas lactantes En vacas lactantes conscientes se llevaron a cabo mediciones electro-magneticas del flujo sanguineo en la arteria mamaria y mediciones de la tension arterial en la carotida, con el fin de examinar los receptores adrenergicos en el lecho vascular de la glandula mamaria. Inyecciones intravenosas de adrenalina, noradrenalina, fenilefrina e isoprenalina, antes y despues de administrar substancias bloqueadoras de los receptores α o β, podian poner en evidencia que los vasos sanguineos de la mama de vaca lactante interesan tanto los receptores adrenergicos α como los β.

Zusammenfassung Vitamin B12-Bilanz zwischen der Aufnahme durch das Euter und der Sekretion in die Milch bei der Kuh Bei einer laktierenden Kuh wurde der Blutflus durch die A. pudenda externa der rechten Euterhalfte elektromagnetisch gemessen. Einunddreisig arterio-venose (A-V) Konzentrations-differenzen uber das Euter zeigten eine Vitamin B12-Aufnahme durch die Milchdruse. Die mittlere A-V-Differenz war vom Null-Wert signifikant unterschiedlich (p < 0,05). Die mittlere Extraktionsrate belief sich auf 5,5%. Die Aufnahme uberschritt die Sekretion von 17%, ohne jedoch signifikant zu sein. Die Korrelation zwischen der A-V-Differenz und der arteriellen Konzentration war hoch signifikant (p

Zusammenfassung Der Effekt einer intramammaren Kolchizin-Infusion auf den mammaren Blutflus bei laktierenden Ziegen Es wurde der Effekt einer intramammaren Kolchizin-Infusion auf den mammaren Blutflus (MBF) bei laktierenden Ziegen untersucht. Die Ergebnisse konnen in zwei Gruppen eingeteilt werden: in der ersten Gruppe wurde der MBF nicht signifikant verandert, in der zweiten Gruppe stieg der MBF von der 8. bis zur 24. Stunde nach der Infusion an und erreichte ein Maximum zwischen der 16. und 24. Stunde nach der Infusion, das bis zu 100% hoher lag als der normale Durchflus. Die Milchleistung (MY) sank in beiden Gruppen signifikant wahrend des Versuches ab, so das das MBF/MY-Verhaltnis in beiden Gruppen sehr hoch lag. Nach der intramammaren Kolchizin-Infusion traten bei allen Tieren Fieber, eine Verhartung der Milchdruse und positive CMT (California Mastitis Test)-Werte auf. Diese klinischen Erscheinungen und der erhohte MBF konnten nicht durch Filtern der Kolchizin-Losung durch eine PTGC-Millpore-Membran verhindert werden.

Isolated mammary glands of lactating goats were perfused with heparinized and oxygenated blood for 8 to 15h. Adequate quantities of glucose, acetate, and amino acids were added to the perfusate. After addition of propionate to the perfusion blood, concentrations of odd-numbered and of monomethyl-substituted fatty acids other than those with iso and anteiso configuration increased in the milk fat. These acids seem to be synthesized de novo in the mammary gland. The increase of C 17.0 concentration was weak and problematic. We suggest that propionate is acting as a precursor for monomethyl-substituted fatty acids by way of methylmalonyl-CoA. The activating effect of propionate administration upon milk fatty acid production was largest for odd-numbered followed by monomethyl-substituted fatty acids. No increase of iso acids was observed in milk fat in the propionate-infused glands whereas the increase of anteiso acids was extremely small. This agrees with the conception that iso and anteiso fatty acids are synthesized by rumen bacteria.

Milking characteristics were measured on 19 primiparous cows of the Red Pied breed at morning milkings. Measurements included maximum and average rate of flow, yield of milk through the 1st, 2nd, and 3rd min, amount of milk through the first 2 and first 3min of milking, and milking time. Subsequently cows were slaughtered and teats immediately removed. Adrenoceptors on membranes isolated from teat tissue were identified by radiolabeled antagonists: [ 3 H]dihydroalprenolol for β 2 -adrenoceptors, [ 3 H] rauwolscine for α 2 -adrenoceptors, and [ 3 H] prazosin for α 2 -adrenoceptors. Measurements of milking characteristics were highly repeatable within cow. Cows showed five distinct and significantly different milk flow patterns, which were characteristic for fast (type I, II), relatively fast (type III), and slow (type IV, V) milking cows. Covariance analysis for the five different types revealed an average regression between α 2 -adrenoceptor density and milking rate 1st min as well as between β 2 : α 2 -adrenoceptor ratios and milking rate 2nd min and milking time. A hypothesis is presented to explain these observations. During milking, tone of efferent sympathetic nerves in the teat is low. This phenomenon is more pronounced in fast milking cows. The typical presynaptic adrenoceptor pattern in the teat of fast milkers (low β 2 : α 2 -adrenoceptor ratio) results in a decline of norepinephrine release by feedback mechanisms.

SummaryOxytocin was infused for 60 min into the jugular vein of 8 lactating cows with full udders before milking. Under these circumstances milk loss occurred spontaneously in 3 cows and was evoked in 5 cows by reducing pressure around one teat (–30 cm water) using a plethysmographic chamber. Milk loss was measured continuously. The postsynaptic α-blocking agent prazosin (PRZS) injected either into the udder artery (2 or 5 mg) or into the jugular vein (200 mg) consistently induced a significant increase in milk leakage. It is suggested that PRZS effectively inhibits α-adrenoceptors in the teat sphincter muscles and thus promotes the action of β-adrenoceptors, in this way inducing relaxation of the teat sphincter.

SUMMARYSeven lactating goat mammary glands from 6 goats were perfused for several hours in the presence of [U-14C]L-leucine (4 experiments) or [2-3H; l-14C]DL-leucine (3 experiments) and received adequate quantities of glucose, acetate and amino acids. Radioactivity in casein was mainly recovered in leucine and 90% of casein leucine was derived from free plasma leucine. About 64% of the leucine molecules were used for casein synthesis. Up to 12% of the molecules were channelled into lipid synthesis, while the remaining (up to 24%) were metabolized to CO2. From the3H/14C ratio of casein and casein leucine, it was calculated that 70–80% of the leucine molecules were reversibly transaminated before their incorporation into milk protein. However, only 4–8% of the plasma leucine molecules were transaminated during passage through the udder. Different pools for oxidation and for protein synthesis may be present in the goat mammary gland.

The isolated mammary glands of six lactating goats were perfused with heparinized and oxygenated blood for 8 to 11 h. Adequate quantities of glucose, acetate and amino acids (including valine) were added to the perfusate. Either unlabelled valerate or unlabelled isobutyrate was added in excess to the perfusate of one gland, while the respective symmetrical gland was used as a control. After the administration of valerate, the proportions of the odd-numbered fatty acids (C11:0, C13:0, C15:0) in the milk fat, collected every hour during perfusion, rose progressively after 5 h until the end. The synthesis of milk fatty acids from valerate is discussed. After isobutyrate was added to the perfusate, isoC12:O, isoC14:0 and isoC16:0 in the milk fat increased as compared to the control. The effect of isobutyrate indicated that valine acted as a precursor of milk iso-branched fatty acids after its metabolisation to isobutyryl-CoA. During perfusion in the presence of the complete substrate mixture, the proportion of certain major milk fatty acids (C10:0, C12:0, C14:0 and C16:0) increased, whereas the proportion of C18:0 and C18:1 decreased. These effects have been ascribed to the presence of acetate and beta-hydroxybutyrate in the substrate mixture.

Milking characteristics were measured on 14 cows at morning milkings. After collection of blood, cows were slaughtered and teats were removed. β 2 -Adrenoceptors on teat tissue and lymphocyte membranes were identified by binding of [ 3 H]dihydroalprenolol. For the determination of α 2 -adrenoceptors on teat tissue and blood platelet membranes, [ 3 H]rauwolscine was used. In teat tissue and blood cells, except for the amount of milk collected during the 3rd min, all other milking parameters were highly correlated with the ratio of β 2 -adrenoceptors to α 2 -adrenoceptors. Good milkability appears to be associated with low ratio of β 2 -adrenoceptors to α 2 -adrenoceptors densities in teat tissue, and a high ratio of β 2 - to α 2 -adrenoceptors densities in blood cells. We postulated earlier that a low ratio of β 2 to α 2 -adrenoceptors in teat tissue of fast milking cows probably reflects changes of mainly prejunctional adrenoceptors. From our results on blood cells, we are now hypothesizing that in teat tissue prejunctional and extra junctional α 2 - and β 2 -adrenoceptors might have been identified together, whereas α 2 - and β 2 -adrenoceptors identified on blood platelets and lymphocytes, respectively, are reflecting by preference extra junctional adrenoceptors. Extra junctional adrenoceptors are activated primarily by circulating epinephrine. The high ratio of β 2 - to α 2 -adrenoceptors observed in blood cells of fast milking cows might indicate a decreased vasomotor tone in the teat and an increased dilatation of the teat sphincter in these animals.

Four lactating goat mammary glands were perfused for several hours in the presence of ornithine labeled with 1-carbon-14 and δ -nitrogen-15 or 5-hydrogen-3 and received adequate quantities ff glucose, acetate, and amino acids. For the first label carbon and nitrogen were incorporated in casein of milk. After isolation of the casein amino acids the carbon-14 was incorporated into proline only while nitrogen-15 was localized in aspartic acid, glutamic acid, alanine, serine, glycine, and the branched-chain amino acids. In the experiments with hydrogen-3 labeled ornithine, no reversible transamination of ornithine could be measured during passage through the udder. After incubation in vitro of goat blood in the presence of the labeled ornithine, no nitrogen-15 could be detected in other free amino acids of plasma. Ornithine is transaminated by the udder itself. The δ -amino group of ornithine contributed nitrogen for the synthesis of several nonessential amino acids in the mammary gland.

The effects of perphenazine on galactopoiesis were studied in 52 goats in the phase of declining lactation (September–December). At the beginning of September, perphenazine (1 mg) was stereotaxically implanted into the hypothalamus, sham-implantations being performed on control animals. After the operation milk yield decreased and stabilized at a new starting level in most animals of both groups. The average weekly milk yield of the sham-implanted goats gradually fell during the experimental period. This progressive decline in yield was greatly reduced if perphenazine had been implanted in the median eminence (ME). No galactopoietic effects were observed when the implantation was localized outside the ME.

SummaryOne half-udder from a lactating cow was perfused for 110 min with blood containing 1 mc of [1-14C]butyrate. Inactive sodium butyrate was added at the eightieth minute. The volume of milk collected was 320 ml. One half-udder from another cow was perfused for 120 min in the presence of 0·5 mc [3-14C]butyrate, inactive sodium acetate being added at the sixtieth minute. The volume of milk collected was 150 ml.The total amount of14CO2recovered was 5·7% of the [1-14C]butyrate given and 7·6% of the [3-14C]butyrate given. In both instances casein, followed by the volatile fatty acids, showed the highest specific activity of the constituents isolated from the milk. The glyceride fatty acids in the udder were fifty times as active as those in the milk. With [3-14C]butyrate the activity of the total fatty acids amounted to 24% and that of total lactose to 0·38% of the added14C. Butyrate did not appear to be used for glycogenesis in the perfused gland. The specific activity of the lower fatty acids of both the udder and the milk increased stepwise with increasing chain length to reach a maximum at C10. A satisfactory explanation for this peculiar14C distribution cannot be given at the present time. There was no evidence of direct esterification of butyrate. Most of the activity of casein was due to labelled glutamic and aspartic acids, the activity of the former being four times as high as that of the latter. The acids of the Krebs cycle isolated from the udder tissue when [3-14C]butyrate was given showed very high activity. No striking differences were observed between the results of the two experiments. It is concluded that butyrate is split into two C2components which behave identically. These are utilized for fatty acid synthesis and take part in the Krebs cycle. The relative14C distribution between the components isolated from milk and those from tissue may be a reflexion of the secretory processes in the udder cells, synthesized fat tending to be secreted in the alveoli after the other constituents.

SUMMARY One-half of a lactating cow's udder was perfused with heparinized and oxygenated cow's blood at 38" for 150 minutes; 30 minutes after the onset of the perfusion, approximately 200 pc of stearate-l-C" (albumin-bound) was added to the perfusing blood, together with inactive acetate and glucose. Almost all the blood's stearate-l-C1* was absorbed by the gland, and much of the added Cl4 was recovered horn the glycerides of the udder tissue. Stearic acid and oleic acid of the glycerides showed significant specific activities. Negligible activities were detected in the shorter chain fatty acids of the glycerides, in citric acid, and in CO*, indicating that stearic acid was broken down to only a very small extent.

1. Lactating mammary glands of sheep were perfused for several hours in the presence of dl-[2−14C]ornithine or dl-[5−14C]arginine and received adequate quantities of acetate, glucose and amino acids. 2. In the [14C]ornithine experiment 1·4% of the casein and 1% of the expired carbon dioxide came from added ornithine; 96% of the total radioactivity in casein was recovered in proline; 13% of the proline of casein originated from plasma ornithine. 3. In this experiment the results of chemical degradation of proline of casein as well as relative specific activities in the isolated products are consistent with the view that ornithine is metabolized, by way of glutamic γ-semialdehyde, to proline or glutamic acid. 4. In the [14C]arginine experiments 3% of the casein and 1% of the expired carbon dioxide came from arginine; 84% of the arginine and 9% of the proline of casein originated from plasma arginine. 5. In these experiments the relative specific activities of arginine, ornithine and proline in plasma are in agreement with the view that arginine is metabolized by way of ornithine to proline. The conversion of arginine into ornithine is probably catalysed by arginase, so that arginase in mammary tissue may be involved in the process of milk synthesis.

SummaryLactating mammary glands of sheep and goats were perfused for several hours in the presence of [1-14C]palmitate or [1-14C]oleate. Adequate quantities of acetate, glucose, amino acids and chylomicrons were added to the perfusate.The fall in specific activity of [1-14C]palmitic acid or [1-14C]oleic acid across the gland and the labelling of milk triglyceride fatty acids indicates an extensive transfer of radioactivity from plasma free fatty acids (FFA). The plasma triglycerides showed large arterio-venous differences in concentration. The small [14C] incorporation in plasma triglycerides decreased across the gland. In a control experiment triglycerides were also slightly labelled.There were no significant arterio-venous differences in cholesterol esters and their fatty acid composition showed only slight changes during passage through the gland. Their specific activity showed a small rise across the gland.In milk components, the [14C] was mainly localized in the triglycerides. An appreciable proportion of the palmitoleate is derived from palmitate by dehydrogenation within the gland, while there is no evidence for the hydrogenation of oleic acid to stearic acid. Elongation of palmitic acid to C18-acids does not occur to any important extent. FFA are catabolized to a variable extent by the gland.The role of FFA in labelling of milk and blood plasma fatty acid fraction is discussed.

SummaryRhythmic motility of teats in lactating cows in vivo was studied by an improved plethysmographic technique. Oxytocin was infused intravenously and drugs were injected into the artery of the filled udder. The β-adrenergic agent, isoprenaline, induced relaxation of the teats whereas the α-adrenergic agents phenylephrine and noradrenaline, elicited contraction. In one animal however, noradrenaline always exerted a biphasic effect. Pre-treatment with propranolol, a β-adrenergic blocking agent, changed the biphasic effect into a purely activating response. Adrenaline, which exhibits both a and β effects, induced relaxation, but after propranolol treatment relaxation was abolished and even converted into contraction of the teat. It seems clear that both α and β adrenoceptors are present in longitudinal smooth muscles of the teats.Milk losses as intermittent spurts were observed in several cows. Spurts occurred synchronously with rhythmical teat motility in the filled udder during oxytocin infusion. The intensity of milk leakage was increased by isoprenaline and inhibited by noradrenaline, indicating the presence of α and β receptors in teat sphincter muscles. Starting and stopping of milk spurts in correlation with rhythmical teat contractions were studied by audiovisual synchronization of video recording tape. The most common type of spurt began near the middle of the teat's relaxation phase and ended either just before or exactly at the beginning of the contraction phase. Interruption of the spurt is primarily due to closure of the streak canal.

Zusammenfassung Chemische Bestandteile im Gewebe und in der Zystenflussigkeit der Bartholinischen Drusen bei Kuhen Im Gewebe und in der Zystenflussigkeit der Bartholinischen Drusen von pluriparen Kuhen wurden das freie Glyzerin, die Phospholipide und die Triglyzeride bestimmt. Im Drusengewebe wurden sehr niedrige Konzentrationen von Phosphorylcholin gefunden. Hingegen war diese Verbindung in der Zystenflussigkeit nicht vorhanden. Glyzerylphosphorylcholin und Lactose konnten weder in der Zystenflussigkeit noch im Drusengewebe nachgewiesen werden. In der Zystenflussigkeit wurden neunzehn freie Aminosauren sowie Harnstoff, Zitronensaure und Milchsaure gefunden. In hochviskosen Zystenflussigkeiten war die Konzentration der Aminosauren hoher als in wasserigen Flussigkeiten. Die Harnstoffkonzentration war in der Zystenflussigkeit ungefahr gleich hoch wie im Blutplasma. Resume Composants chimiques dans le tissu et le liquide kystique des glandes vulvo-vaginales chez des vaches On a determine la glycerine, les phospholipides et les triglycerides dans le tissu et le liquide kystique des glandes de Bartholin chez des vaches multipares. On a trouve des concentrations tres faibles de phosphorylcholine dans le tissu glandulaire mais pas dans le liquide kystique. La glycerylphosphoryl-choline et le lactose n'ont ete trouves ni dans le liquide ni dans le tissu. On a trouve dix-neuf acides amines libres, de l'uree, de l'acide citrique et lactique dans le liquide. La concentration en acides amines fut plus elevee dans un liquide fortement visqueux que dans un liquide aqueux. La concentration en uree dans le liquide fut a peu pres la meme que dans le plasma sanguin. Resumen Constituyentes bioquimicos en el tejido y liquido quistico de las glandulas de Bartholin en vacas Se valoraron en el tejido y en el liquido quistico de las glandulas de Bartholin de vacas pluriparas la glicerina libre, los fosfolipidos y los trigliceridos. En el tejido glandular se hallaron concentraciones muy reducidas de fosforilcolina. Esta substancia estaba presente en el liquido quistico en concentracion mayor. No se detectaron glicerilfosforilcolina ni lactosa en el liquido quistico ni en el tejido glandular. En el liquido quistico se identificaron diecinueve aminoacidos libres, urea, acido citrico y acido lactico. En los liquidos quisticos viscosos era mayor la concentracion de los acidos que en los fluidos acuosos. La concentracion de urea en el liquido quistico era casi la misma que en el plasma sanguineo.

Five lactating goats were milked twice daily. After a control period of 3 days, they were fasted for 48 hr. The milk was collected at each milking. At the end of the fasting period, milk yield fell to 28% and milk fat to 55% of the original yield. The percentage of milk fat increased. Generally, the relative concentrations of fatty acids with less than or equal to 16 carbons, containing even and odd-numbered straight-chain as well as monomethyl-substituted fatty acids of the milk fat, decreased significantly 24 hr after food was withheld. The decrease was most pronounced for the fatty acids with the shortest chain lengths. Longer-chain acids increased or did not change. Iso and anteiso-acids seemed to follow the same, although less pronounced trend, the effect being obvious after 48 hr of fasting. It is suggested that the decline in the proportions of fatty acids with less than or equal to 16 carbons was due to the inhibition of mammary gland synthesis. The increase in the proportions of longer-chain fatty acids was ascribed to adipose tissue lipolysis.

Summary Angiotensin was injected into either the jugular vein or the carotid artery in lactating cows and goats. It was also either injected or infused into the third ventricle of goats. In goats intraventricular administration resulted consistently in a drinking response, and a pituitary antidiuretic effect, whereas milk ejection was observed occasionally. Injection of angiotensin into the carotid artery provoked both drinking and milk ejection. In cows, single intravenous and intracaronotid injections of angiotensin induced drinking. After intracaronotid injection, drinking responses were more pronounced and occurred more frequently. Intracaronotid administration of 500 μg. angiotensin frequently induced milk ejection. Zusammenfassung Der Einflus von Angiotensin auf den Wasserhaushalt und das Milcheinschiesen bei Wiederkauern Bei laktierenden Kuhen und Ziegen wurde Angiotensin entweder in die Vena jugularis oder in die Arteria carotis injiziert. Auch wurde es in den dritten Hirnventrikel von Ziegen infundiert. Bei Ziegen trat nach der intraventrikularen Applikation Trinken und eine hypophysar ausgeloste Antidiurese auf. Gelegentlich war auch Milcheinschiesen festzustellen. Die Injektion von Angiotensin in die Arteria carotis bewirkte sowohl Trinken als auch Milcheinschiesen. Bei Kuhen induzierte eine einmalige intravenose oder intraarterielle Injektion von Angiotensin Trinken. Bei der intraarteriellen Injektion war das Trinken haufiger und starker. Intraarterielle Applikation von 500 μg Angiotensin loste ebenfalls haufig Milcheinschiesen aus. Resume L'influence de l'Angiotensin sur l'equilibre aqueux et l'ejection lactee chez les ruminants De l'Angiotensin fut injectee soit dans la veine jugulaire soit dans l'artere carotide chez des vaches et des chevres en lactation. On a egalement infuse de l'Angiotensin dans le troisieme ventricule cervical chez des chevres. L'action de boire et le declenchement d'une antidiurese hypophysaire sont intervenus apres l'application intraventriculaire. On a egalement constate a l'occasion une ejection lactee. L'injection d'Angiotensin dans l'artere carotide a aussi bien declenche une action de boire que l'ejection lactee. Une seule injection i/v ou i/a chez les vaches a induit une action de boire qui fut plus frequente et plus forte apres l'injection intraarterielle. L'application i/a de 500 μg d'Angiotensin declenche egalement une ejection lactee. Resumen La influenca de la angiotensina sobre el equilibrio acuoso y la eyeccion lactea en ruminantes Se inyecto angiotensina a vacas y cabras en lactacion, bien en la vena yugular, bien en la arteria carotida. Tambien se infundio en el tercer ventriculo cerebral de cabras. En las cabras aparecio, tras la aplicacion intraventricular una sensacion de sed y una antidiuresis hipofisaria. Tambien se constato, en ocasiones, una eyeccion lactea. La inyeccion de angiotensina en la carotida ocasionaba sed y eyeccion lactea. En vacas inducia sed la inyeccion intravenosa o intraarterial, unica, de angiotensina. En la inyeccion intraarterial era la sed mas frecuente e intensa. La aplicacion i. a. de 500 μg. de angiotensina tambien desencadenaba con frecuencia la eyeccion lactea.

SummaryThe effect of intramammary infusion of Escherichia coli endotoxin upon mammary blood flow was studied in lactating goats and cows. Blood flow was recorded by means of an electromagnetic flow probe chronically implanted around one mammary artery.Endotoxin mastitis was always accompanied by a significant increase in mammary blood flow, characterized by 2 conspicuous peaks. The flow returned to control values by the thirteenth hour after infusion. Other symptoms of acute mastitis were: fever, increased heart rate, swelling, heat and pain of the gland, increased chloride and total cell count in milk.

SummarySubcutaneous injections of 30 mg atropine into lactating cows induced a 20–40% decrease of free amino acid (AA) levels in arterial plasma. Minimum levels were observed after 30–50 min. The decline persisted for more than 6 h. The greatest fall in concentration was noted for tyrosine, methionine, lysine, arginine, phenylalanine and threonine. Arterial glucose levels remained unaffected. The effect of atropine on milk secretion was studied in 2 cows which were milked every hour with the aid of oxytocin. Maximal effects were observed after 3–4 h. They included reduction in concentration of casein and ±-lactalbumin (±-la) and a decline in production of milk (20%), casein (35%), ±-la (45%) and lactose (18%). Uptake by the lactating udder over a period of about 1 h after injection of atropine was studied in 2 cows. Mammary blood flow and glucose uptake remained unaffected. There was a positive correlation between arteriovenous differences of essential AA and arterial plasma concentrations. The uptake of essential AA decreased by approximately 50 %. There was no evidence that atropine has a direct inhibiting effect on the udder. It is suggested that the decrease of ±-la synthesis might induce an inhibition of lactose synthesis and milk production.

SummaryPerphenazine (0·8–1mg) caused udder growth and artificial induction of lactation, when stereotaxically implanted into the median eminence of virgin female goats. Sham implantations into the median eminence or implantation of perphenazine into sites of the hypothalamus not in the immediate proximity of the median eminence were ineffective. Fourteen–twenty-two d after implantation the goats were milked for the first time. Maximal milk yields of 250–1050 ml/d were achieved 3–5 months later. Udder development and induction of lactation during the premilking period were exclusively due to the action of perphenazine. It is likely that after implantation the milking stimulus played a synergic role with perphenazine in the progressive increase and the maintenance of lactation. Apparently no side effects were caused by the drug. Implantation of small doses of perphenazine in the hypothalamus might be a suitable technique for studying the physiological effects of increased levels of endogenous prolactin in goats.

The effect of intramammary (i.mam.) infusion ofEscherichia coli lipopolysaccharides (LPS) upon mammary blood flow (MBF) was studied in lactating goats using the electromagnetic flow technique. After i.mam. LPS administration mastitis, accompanied by a significant increase in MBF, occurred. This phenomenon showed two conspicuous peaks which occurred 11/2h and 8–10h after LPS administration. Other symptoms were: fever, increased heart rate, swelling and pain of the gland, increased chloride (MCl−) and total cell count (TC) in milk. Since there was a marked coincidence between the increment stage of fever and the break-down of MBF peak I, studies were performed to evaluate the possible role of fever in this typical biphasis MBF pattern.

SummarySpontaneous rhythmical contractions of the teats of living cows were recorded by a plethysmographical method. These contractions were inhibited by isoproterenol, adrenaline, isoxsuprine and phentolamine, but were activated by phenylephrine. Noradrenaline induced activation which was often followed by inhibition.These results obtained in vivo were in agreement with responses obtained in vitro. Apparently beta sympathomimetic effects are evoked easily under in vivo conditions.

SUMMARYThe effects of serotonin, injected into one udder artery, on teat smooth muscle function were investigated in four lactating cows. Motility of longitudinal smooth muscles was recorded by a plethysmographic technique, and sphincter function by measuring milk leakage from the full udder. Serotonin (40, 120 and 360 μg) activated teat muscle tonicity and reduced the volume of milk leakage. The effects on longitudinal smooth muscles were reduced by mianserin and ketanserin (0·375, 1·5 and 6 mg) and by methysergide (1·5 mg). These blocking substances were also effective (0·2, 0·6 and 1·8 mg respectively) in antagonizing the inhibiting action of serotonin on milk leakage. It is suggested that serotonin effects are mediated by receptors of the S2-type.

SummaryA lactating mammary gland of a goat was perfused for 9 h in the presence of [U-14C]-l-threonine and received adequate quantities of glucose, acetate and amino acids. Two lactating sheep udders were likewise perfused in the presence of [U-14C]-l-phenylalanine: the plasma levels of phenylalanine in the first of these experiments were 4 times higher than in the second.In the [14C]threonine experiment, 4 % of the casein and 0·4 % of the expired CO2were derived from threonine; 85 % of the threonine and 1·6 % of the glycine residues in casein originated from plasma threonine. Small14C levels were found in glutamic acid, aspartic acid and serine of casein. The relative specific activities amongst the casein amino acids and the appearance of appreciable labelling in plasma glycine are consistent with the view that threonine is split by threonine aldolase.In the [14C]phenylalanine experiments virtually no radioactivity was detected in CO2, lactose or citric acid, indicating that this substrate is not broken down by mammary tissue. In the second experiment, 96 % of the phenylalanine and 0·3 % of the tyrosine of casein originated from plasma phenylalanine. In the first experiment, a 30-fold higher14C incorporation into casein tyrosine relative to phenylalanine was observed. The possible significance of the phenylalanine concentration in the plasma on the degree of conversion of phenylalanine into tyrosine within the mammary gland is discussed.

SummaryThe plasma levels of individual amino acids were studied in 6 dairy cows from 4 days before to 3 days after calving. During this sampling period, the concentrations of 13 amino acids showed significant changes. The levels of several amino acids were depressed markedly in the sample collected immediately before calving. Following parturition, the concentration of most amino acids gradually returned to values obtained 3 days before calving. The glutamine and alanine contents of the plasma rose to a peak value 1 day after calving and subsequently decreased. The mean concentrations of glycine and α-aminobutyric acid did not change before parturition but rose significantly thereafter. These observations are discussed in terms of amino-acid utilization for milk protein synthesis and gluconeogenesis at the onset of lactation. The changes in plasma amino acid levels appear to be synchronized with those reported for prolactin and progesterone in the 24 h before parturition. This may indicate an important influence of both hormones on the lactogenic process in the cow. The highly significant correlations obtained between the concentrations of 14 individual amino acids are discussed.

Summary Twenty-four primiparous heifers were separated from their calves immediately after parturition in such a way that they could neither see nor hear each other. Several hours later, cannulas were introduced into the teats of the heifers. The calves were brought in front of their dams but suckling or contact with the udder was avoided. Calves and dams were watched for 15–20 minutes. The presence of the calf induced definite milk ejection starting after a short latency in 13 of the heifers. Good maternal behaviour and milk ejection were usually allied. These results are discussed in connection with the functions of the limbic system and the hypothalamus. Zusammenfassung Die Milchejektion bei primiparen Farsen wahrend der Anwesenheit der Kalber Es wurden 24 Farsen direkt nach der Geburt von ihren Kalbern getrennt, und zwar so, das sie sich weder horen noch sehen konnten. Einige Stunden spater wurden in die Zitzen der Farsen Kannulen eingefuhrt. Die Kalber wurden so an den Kopf der Farsen gebracht, das weder Saugen noch ein Kontakt mit dem Euter moglich war. Kalber und Farsen wurden wahrend 15–20 Minuten beobachtet. Bei 13 Farsen wurde durch die Anwesenheit der Kalber ein eindeutiger Milchflus hervorgerufen. Gewohnlich traten gutes Mutterverhalten und Milchejektion zusammen auf. Diese Resultate werden in Zusammenhang mit den Funktionen des limbischen Systems und des Hypothalamus diskutiert. Resume Ejection de lait chez des genisses primipares en presence de leurs veaux On separe vingt quatre genisses primipares de leurs veaux, immediatement apres la naissance, de telle sorte qu'ils ne puissent ni se voir, ni s'entendre. Quelques heures plus tard, on introduit des canules dans les trayons des genisses. Les veaux sont mis en presence de leurs meres, sans qu'il y ait possibilite de tetee ou de contact avec la mamelle. On observe veaux et genisses pendant 15–20 minutes. La presence du veau induit une nette ejection de lait, debutant apres une breve latence, chez 13 genisses. En general, un bon comportement maternel va de pair avec une ejection du lait. On discute ces resultats, en correlation avec les fonctions du systeme limbique et de l'hypothalamus. Resumen Evacuacion lactea en vaquillonas primiparas estando presentes sus terneros Veinticuatro vaquillonas primiparas se separaron de sus terneros inmediatamente despues del parto, de manera que no se podian ver ni oir entre si. Algunas horas despues se introdujeron canulas en los conductos galactoforos de las vacas. Los terneros se colocaron frente a sus madres, sin que pudiesen mamar ni entrar en contacto con la ubre. Los terneros y vaquillonas se observaron durante 15–20 minutos. En 13 vacas inducia la presencia del ternero correspondiente la evacuacion definitiva de leche, iniciandose despues de una latencia breve. Por lo general, estaban relacionados el comportaminto maternal bueno y la evacuacion de leche. Estos resultados se discuten en conexion con las funciones del sistema limbico y del hipotalamo.

1. The distributions of (14)C have been compared in the glucose and galactose moieties of lactose obtained from cows' udders perfused with blood containing [1-(14)C]-, [2-(14)C]- and [6-(14)C]-glucose. The (14)C of the glucose moiety was found in the same position as that of the administered glucose, but in the galactose moiety the (14)C from [2-(14)C]glucose was extensively randomized into positions 1 and 3. It is concluded that the glucose moiety arose from free glucose and the galactose moiety from hexose phosphate intermediates and that the latter reflected the randomization occurring through reactions of the pentose cycle. 2. The proportion of the glucose metabolized via the pentose cycle for those cells making lactose was estimated from the distribution of (14)C in the galactose moiety and found to be about 23% in one experiment and 30% in another experiment. 3. The yield and distribution of (14)C were determined in the glycerol of fat from the tissue in experiments with [2-(14)C]- and [6-(14)C]-glucose. There was a greater randomization of (14)C in the glycerol than in C-1, C-2 and C-3 of the galactose moiety of lactose. The ratio of the yield of (14)C in the glycerol from [2-(14)C]glucose to that of [6-(14)C]glucose was very low and from this ratio it was calculated that less than 10% of the glucose was metabolized by the Embden-Meyerhof pathway and approx. 60-70% was converted into lactose. 4. [6-(14)C]Glucose and [6-(3)H]glucose were used to determine whether the (3)H at the C-6 position remained stable during its conversion into glyceride of fat from the tissue. Twenty-seven per cent of the (3)H was labilized during this conversion. Therefore it was not possible to use [2-(14)C]glucose and [6-(3)H]glucose in a single experiment to measure the relative conversion of the C-2 and C-6 positions of glucose to glycerol.