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Radial oxygen losses (ROL) from the roots of intact rice plants were assayed by the cylindrical Pt electrode technique. At 23°C losses from roots grown in waterlogged soil proved to be about double those from non-waterlogged plants. Cooling which lowers respiratory activity led to increased ROL and it was estimated that at 23°C respiratory activity had been reducing oxygen loss by 8 to 10 10–8g O2 cm–2 root surface min–1 (c. 50 %) in the non waterlogged, and by 4.5 to 5.5 10–8g O2 cm–2 min–1 (2C–30 %) in the waterlogged roots. Lacunae formation occurred nearer to the apex and was eventually more extensive in the waterlogged roots while the presence of more intact and presumably functional tissue in the non-waterlogged roots coincides with the greater respiratory effect noted. Estimated flux rates at 23°C (respiration inactive) were respectively 15–17 × 10–8g O2 cm–2 min–1 (non-waterlogged) and 20–23 × 10–8g O2 cm–2 min–1 (waterlogged). A major part of this difference can probably be accounted for directly by the differences in root porosity, and Meakiness' superimposed upon lower porosity in the non-waterlogged plants may account for the remainder. ROL was also examined in relation to distance from the apex. With respiratory activity lowered by cooling, two patterns of oxygen loss were detected. Pattern I was a property of younger roots of length between 5–9 cm, while pattern 2 was found in longer roots 11–16 cm bearing numerous emergent laterals. In both, ROL fell rapidly towards the base and at 4–5 cm approached zero in pattern 1 and near zero to about 16% of the maximum in pattern 2. The rapid drop in oxygen loss in both patterns which indicates a concomitant decrease in root wall permeability was associated with the appearance of cortical lacunae at 2–3 cm from the apex. In pattern 2 a rise in ROL began at 5–6 cm from the apex. The presence of lateral root initials in both the pericycle and unbroken segments of cortex was associated with maintained permeability in this pattern as well as with the basal increase in ROL. With a 3-electrode system placed around the apical 3 cm regions of waterlogged roots, it was found that ROL was substantially affected by respiratory activity at 0.5 cm, a little less so at 1.7 cm, but much less or not at all at 3 cm from the apex. The drop in respiratory effect parallelled the formation of cortical lacunae.

The more plausible hypotheses regarding the mechanism which controls amphibian embryonic respiration have been reviewed, providing some explanation for the contradictory respiratory ratios between intact and homogenized eggs reported by other investigators.The concentration of embryonic material appears to be of the utmost significance in the relative rates of respiration of homogenized as compared to intact eggs. A close correspondence between increased oxygen uptake and the ATPase activity resulting from homogenization has been demonstrated. This would account for the lack of respiratory effect by 2,4-dinitrophenol which has been described in homogenized eggs of Rana pipiens and Bufo arenarum. Homogenization, as well as 2,4-dinitrophenol could stimulate oxygen uptake by altering the ATP/ADP ratio. By means of ATPase inhibition it has been also demonstrated that the respiration of homogenates is strongly affected by ADP while exogenous ATP is almost without effect.

SummarySN 13592 is characterized by an extremely low acute and chronic oral toxicity in several species. Local irritation effects are absent even upon repeated administration. Continued oral feeding of the drug induces an anemia which gradually disappears after the drug is withdrawn. Although there were no consistent effects on blood pressure and heart rate, a respiratory effect was noted. Smooth muscle was generally stimulated by this compound.

Most knowledge of respiratory changes due to hormones has been gained from studies which were made years ago. Even that knowledge is limited and incomplete. In fact, modem models of the control of respiration do not include or consider the role of hormones (1, 2).

Am nichtnarkotisierten Hund wurden nach den Methoden von Schroeder vergleichende Untersuchungen uber die Atmungs- und Kreislaufwirkung von Adenosin, Muskeladenylsaure und Adenosintriphosphorsaure angestellt. Im Unterschied zu den Ergebnissen an narkotisierten Tieren fanden wir ausschlieslich eine atmungserregende Wirkung der Adenosinkorper. Der bekannte Blutdruckabfall war — im Gegensatz zur Bradykardie beim Tier in Narkose — von einer Tachykardie begleitet. Der Blutdruckabfall scheint den Kreislaufanalysen nach Wezler und Boger zufolge vor allem durch periphere Gefaserweiterung zustande zu kommen. Die Extremitatendurchblutung war jedoch nur geringgradig vermehrt. Die molaren Wirkungsstarken von Adenosin, AMP und (ATP + ADP) verhielten sich an Atmung und Kreislauf etwa wie 1 : 1,3 : 2,5. Die Befunde werden mit den Ergebnissen fruherer Arbeiten verglichen und in ihrer moglichen therapeutischen Bedeutung diskutiert.

1. 1. The normal respiratory effect of CO2 in avian divers has been studied. Domestic ducks (“white Pekin”) served as subjects. 2. 2. The respiratory minute volume (RMV), tidal volume (TV) and respiratory frequency (RF) were recorded. 3. 3. The RMV almost always increased when the ducks breathed gas mixtures with a high content of CO2. 4. 4. The RMV rose due to an augmentation of TV which more than compensated for the tendency of RF to decrease with increasing CO2-concentrations in the inspired air. 5. 5. These findings confirm the observation by Orr & Watson (1913) and Hiestand & Randall (1941), who found that high concentrations of CO2 in the inspired air cause transient periods of apnoea in the duck. However, they do not support the conclusion that CO2 is a respiratory suppressor in diving birds, for the RMV was not reduced until the CO2-concentrations inhaled were raised well above those found in the lungs of diving ducks (Andersen, 1959).

Insulin depressed hepatic cell respiration in the presence of 2-deoxyglucose by enhancing the uptake of this glycolytic inhibitor. Sodium dodecyl sulfate (SDS) showed little to no respiratory effect in such a system. Both insulin alone and SDS alone enhanced hepatic respiratory rates in the absence of glycolytic inhibitor. In the presence of both insulin and SDS these rates were increased to an extent greater than that observed for either substance alone.

There has been much lay and medical concern regarding toxic effects of insecticides on the general population. In addition to direct toxic effects, it is suspected that insecticidal application has deleterious physical effects on persons with respiratory diseases. To evaluate some of these problems, the authors have attempted to quantitate actual absorption, symptoms, and laboratory evidence of intoxication in persons with varying degrees of exposure to parathion. By means of controlled observations, the respiratory effect of application of this compound on persons with bronchial asthma was also measured. The results suggest that the effect of this chemical on the general population is negligible.

1. 1. The respiratory effect of CO 2 production and O 2 consumption by dehydrated alfalfa meal in closed systems has been studied further. 2. 2. Increasing the water level and/or the temperature had the effect of increasing the respiratory effect and increasing the ascorbic acid (AA) destruction. 3. 3. Adding AA to a reconstituted system in graded amounts produced graded increases in the CO 2 output. 4. 4. Adding AA to alfalfa autoclaved in tubes with low, medium, and high levels of water produced an increase in CO 2 at all levels, the effect tending to be more pronounced at the higher levels. 5. 5. Adding AA to alfalfa autoclaved outside of the tubes gave an increase in CO 2 in some cases, and an irregular effect in other cases. 6. 6. The addition of NaCN to reconstituted alfalfa systems caused an inhibition of the respiratory effect. 7. 7. In an artificial system, AA with the help of a copper catalyst gave rise to significant amounts of CO 2 , whereas no effect was observed with oxalic, tartaric, citric, or lactic acid under this system. 8. 8. Adding copper in the form of a cuprocyanide complex to the artificial system produced much less CO 2 than when it was added in the form of cupric chloride. 9. 9. The above facts are discussed in relation to a new theory to account for the respiratory effect in the natural system.