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SummarySix methods useful in producing experimental hypertension in other laboratory animals were studied in rhesus monkeys. Two methods involving direct constriction of the renal arteries either by silk ligatures or small transparent plastic clamps resulted in a significant incidence of hypertension. Of 13 animals which survived 23 days or longer after renal artery constriction, 10 developed hypertension. The degree of constriction was critical, and a significant proportion of the animals succumbed in acute post-operative renal failure. Four other methods used successfully in rats, rabbits, or dogs were ineffective in the monkey. These included: (1) unilateral temporary renal occlusion and contralateral nephrectomy; (2) unilateral silk perinephritis; (3) unilateral silk perinephritis and contralateral nephrectomy; and (4) bilateral silk perinephritis. Administration of large oral doses of sodium chloride per se did not induce hypertension, nor did it increase the effectiveness of any of the above 4 proce...

Summary and Conclusions1. Courses of intramuscular injections of semipurified hog renin from cortex administered to dogs with experimental renal hypertensions of 4 or more years duration produced a significant reduction in blood pressure in those dogs which developed antirenin but not to normotension as previously found in dogs with chronic renal hypertension of 6 to 37 months duration. The 2 dogs which did not develop antirenin showed a maintained chronic pressor effect. 2. Passive immunization with homologous antirenin to hog renin produced a reduction in blood pressure to normotension or near normotension in dogs with experimental renal hypertensions of more than 7 years duration. 3. The mechanism of the decreased response to hog renin therapy in long term experimental renal hypertension in the dog is unknown. The results with passive immunization suggest that a lessened pathogenetic role for renin is not involved nor is progressive arteriolosclerosis. Possibly compensatory hypertensive mechanisms are ...

SummaryA method is described for determination of direct mean systemic blood pressure in the femoral artery of the unanesthetized rabbit. Weekly blood pressures of 24 rabbits, for 3 successive weeks, and of 6 other rabbits, for 12 weeks, are given. Production of persistent renal hypertension, unaccompanied by significant impairment of renal excretory function, is described and illustrated. It is hoped that publication of this method for determination of the blood pressure of the unanesthetized rabbit will stimulate others to employ this animal more often in future studies of experimental hypertension.

SummaryWe have bred and raised a colony of spontaneously hypertensive rabbits. It is concluded that there is a hereditary factor in hypertension and that the characteristic changes of blood pressure in spontaneously hypertensive animals are similar to the normal rabbit population. These findings would indicate that spontaneously hypertensive rabbits have characteristics in common with man in his development of essential hypertension.

SummaryNormal rat kidneys and kidneys with a narrowed renal artery have abundant granules in the juxtaglomerular cells and large quantities of extractable renin. On the other hand, kidneys of rats with desoxycorticosterone hypertension and the “untouched' kidney of rats with unilateral renal hypertension (resulting from narrowing of the contralateral renal artery) both have a virtual absence of juxtaglomerular granules as well as absence of extractable renin. There is so little renin in these kidneys that the renal extracts usually produce a depressor response. Thus, there exists a striking correlation between the amount of juxtaglomerular granulation and the amount of extractable renin in a kidney. This does not prove that these granules are composed of renin but the observations are compatible with such a hypothesis.

SummaryAn increased antihypertensive action of a combination of reserpine and acetazolamide over that produced singly by either drug was demonstrated in metacorticoid hypertensive rats. Acetazolamide alone had a moderate antihypertensive action, and the enhanced reduction in blood pressure following co-treatment was an additive rather than a potentiated effect. The typical hypertensive left ventricular cardiac hypertrophy was significantly reduced in the metacorticoid rats receiving acetazolamide-reserpine.

SummaryThe ability of the microphonic manometer to measure rapidly and simply not only the pressure of the intact rat but also of the rat made hypertensive by the injection of the vascostrictor substances, epinephrine and renin, indicates that it might be of considerable usefulness in studies necessitating frequent or successive blood pressure determinations in the rat.

SummaryUnilateral renal diseases resembling hydronephrosis, pyonephrosis, or pyelonephritis were induced in rats by partial ureteral constriction and intravenous injection of E. coli. Arterial hypertension developed when chronic unilateral renal infection was produced.

SummaryContinued feeding of pepper, mustard and ginger in various diet combinations results in appearance of a statistically significant hypertension in rats. The greatest elevation occurred in a diet containing all 3 condiments; the hypertension from this diet persisted for months after the diet was discontinued. Other combinations were less effective, and work is continuing to determine if any single representative contains the necessary and sufficient factor for the production of hypertension.

SummaryChronic, progressive, non-obstructed, enterococcal pyelonephritis in the rat is not associated with hypertension. It is suggested that this may be related to the absence of significant arteriolar nephrosclerosis.

SummaryThree natural and 2 synthetic estrogens were compared for hypotensive activity in metacorticoid hypertensive rats. The most active compound was 16-epiestriol 3-methyl ether.

ConclusionsThese results indicate that in rats under these conditions, presence or absence of adrenal tissue has no effect on the severity of hypertension produced by desoxy-corticosterone administration.

SummarySingle injections of Bistrium, Apresoline, and Veriloid induced significant temporary reductions in the blood pressure of rats with metacorticoid (post-DCA) hypertension. Similar rats treated chronically with Serpentina root exhibited a sustained depression of blood pressure.