Blood Pressure In Hypertensive Rats Research Articles

A32390A, a new biologically active metabolite. I. Discovery and fermentation studies.

A32390A is an isonitrile-containing derivative of diacyl D-mannitol. The compound is produced in fermentation as the major component of a metabolic complex known as A32390. A32390A inhibits dopamine-beta-hydroxylase reduces heart and adrenal norepinephrine levels, lowers blood pressure in hypertensive rats, and possesses antibiotic activity vs. Gram-positive bacteria and fungi, including Candida albicans. A32390 is produced in submerged culture by a mold, a species of Pyrenochaeta, NRRL-5786. Glucose and sucrose are among the best carbon sources for the biosynthesis of A32390. Mannitol, although a substituent of the A32390A molecule, supports little or no biosynthesis of the compound when employed as the major carbon source for the fermentation. The addition of crotonic acid derivatives. ethanol, or L-histidine to the fermentation medium enhances the level of A32390 produced.

Vascular reactivity in hypertensive rats after treatment with anti-hypertensive agents

Isolated perfused mesenteric arteries obtained from experimental hypertensive rats (spontaneous and deoxycorticosterone/NaCl) exhibit an increased vascular reactivity to noradrenaline and 5-hydroxytryptamine. The dose response curves obtained exhibited in the threshold dose. After 4 weeks of antihypertensive therapy (a combination of hydrallazine, hydrochlorothiazide and reserpine) which lowered the blood pressures of hypertensive rats to normotensive levels the arteries from the hypertensive animals still exhibited an increased reactivity to vasoconstrictor agents. These results support the hypothesis that the increased reactivity observed in hypertensive animals may be partially due to adaptive structural changes in the blood vessels. However, the persistence of the hyperactivity after antihypertensive therapy seriously questions its involvement in the maintenance of the elevated blood pressure.

Drug metabolism in spontaneously hypertensive rats

Summary The in vitro activity of the microsomal enzymes (hydroxylation and N-demethylation), the concentration of the cytochrome P-450 and the hexobarbital sleeping time of hypertensive rats did not differ significantly from those of normotensive rats. On the basis of these findings it is improbable that the increased blood pressure of hypertensive rats results from the changed metabolism of endogenous blood pressure regulating agents disposed by microsomal enzymes.

Effects of chronic administration of prostaglandin E 1 (PGE 1) on arterial blood pressure of unanesthetized hypertensive rats

It has been reported that daily injections of PGE 1 (15 μg/kg, I.P.) for 1 month normalized arterial blood pressures of rats made hypertensive by impeding blood flow to both kidneys. The present experiments were done to confirm the above findings and to test PGE 1 under similar conditions in hypertensive rats with a single ischemic kidney and also in genetically hypertensive rats. Chronic treatment with PGE 1 (15 μg/kg/day, I.P.) was not associated with decreased arterial blood pressure in hypertensive rats.

Time course of decrease in blood pressure and in blood pressure response to vasopressor agents during pregnancy in the rat.

In the unanesthetized normotensive rat blood pressure progressively decreased during the last week of pregnancy as measured with a direct and an indirect method. In renal hypertensive and desoxycorticosterone acetate (DOCA)-salt hypertensive rats blood pressure also decreased at this time. In the unanesthetized normotensive rat the blood pressure response to exogenous rat renin diminished progressively during the last week of pregnancy. Similarly, the blood pressure response to angiotensin II, noradrenaline and tyramine decreased. The decrease in blood pressure induced by acetylcholine was not affected during pregnancy. Determination of the activity of the renin-angiotensin system showed that plasma renin activity was elevated to 3–4 times the control value on day 20–21 of pregnancy, and that plasma renin substrate was decreased on day 14–15. It is suggested that the decrease in blood pressure which occurs during the last week of pregnancy in the rat is mediated through a decreased responsiveness of the cardiovascular system to vasopressor agents.

Reduction by 9-tetrahydrocannabinol in the blood pressure of hypertensive rats bearing regenerated adrenal glands.

A suspension of (-)-Delta(9)-trans-tetrahydrocannabinol (Delta(9)-THC) (3 mg/kg body wt) was administered daily for one week by i.p. injection to female rats showing the syndrome of adrenal regeneration hypertension (ARH). Other ARH rats received no injections or injections of vehicle only. On the first day, Delta(9)-THC decreased the average blood pressure by 38+/-6 mmHg 1 h, 31+/-5 mmHg 3 h, and 11+/-5 mmHg 5 h after injection (n=0). On subsequent days the acute effect disappeared, but statistically highly significant decreases were observed between the blood pressures of the Delta(9)-THC-treated group and those of the other two groups. Plasma corticosterone concentrations, measured on the eighth day of treatment, one hour after injection time, averaged 26.+/-2.7 mug/100 ml in the untreated animals, 26.6+/-2.0 mug/100 ml in the vehicle-injected animnals, and 21.3+/-2.4 mug/100 ml in the animals injected with Delta(9)-THC. The findings indicate that Delta(9)-THC, at a moderate dose for the rat, is capable of lowering the blood pressure in rats suffering from adrenal regeneration hypertension and that chronic administration of Delta(9)-THC does not appear to stimulate the pituitary-adrenal axis, in contrast to reported effects of acute administration (Barry, Perhach & Kubena, 1970).

Influence of sodium withdrawal by a diuretic agent or peritoneal dialysis on arterial pressure in one-kidney Goldblatt hypertension in the rat.

In rats made hypertensive by partial constriction of one renal artery and contralateral nephrectomy, large doses of furosemide had no hypotensive effect. However, when furosemide natriuresis was followed by removal of the clamped kidney, arterial blood pressure was greatly reduced. The fall of blood pressure induced in this manner was significantly correlated with the amount of sodium and water lost. The absence of a hypotensive effect of furosemide in rats with one-kidney Goldblatt hypertension appeared to be due to enhanced renin secretion. Furosemide not followed by nephrectomy caused a fall of blood pressure in rats with one-kidney Goldblatt hypertension after renin-depletion by desoxycorticosterone and salt treatment. Sodium wastage induced by peritoneal dialysis after removing the clamped kidney also lowered the blood pressure of hypertensive rats.

Sulfur-Containing Derivatives of β-Phenethylamine: Methanesulfonamides

N-Methanesulfonyl derivatives of β-phenethylamine, (+)-amphetamine, β-4-aminophenethylamine, and 4-(2-trifluoro-acetamidoethyl)aniline have been prepared. N-Trifluoroacetyl-1-(4-methanesulfonamidophenyl)-2-ethylamine significantly lowered blood pressure in hypertensive rats, and the methanesulfonamide of (+)-amphetamine lowered blood pressure in the dog.

Inhibition of spontaneous sympathetic nerve activity by the antihypertensive agent Wy-8678

Wy-8678 (2,6-dichlorobenzylidene amino guanidine acetate) has recently been shown to reduce blood pressure in hypertensive rats and dogs. This effect has, at least partially, been attributed to an adrenergic neuron blocking effect. The present series of experiments sought to determine whether the compound also influenced central sympathetic outflow. Spontaneous activity was recorded in two post-ganglionic sympathetic nerves, the inferior cardiac and external carotid. Nerve activity could be readily altered by inducing changes in systemic blood pressure by the injection of norepinephrine and nitroglycerin. Intravenous doses of Wy-8678 of 32–320 μg/kg decreased blood pressure and heart rate and inhibited nerve activity in a dose-related manner. It is concluded that the compound reduces central sympathetic outflow and that this action probably contributes to the anti-hypertensive effect.

Influence of protein synthesis inhibitors on circulatory dynamics.

SummaryAcetoxycycloheximide, an inhibitor of protein synthesis at the ribosomes, reduces the blood pressure of normotensive and hypertensive rats. Chloramphenicol, which has a similar but not identical action, also reduces blood pressure of hypertensive rats. The degree of blood pressure depression to both substances is dose-dependent and is appreciable in non-toxic amounts. Puromycin, which inhibits ribosomal synthesis of protein, but through release of rather than suppression of polypeytides, fails to reduce blood pressures at much higher dosage levels relative to toxicity. Blood pressure depression following acetoxycycloheximide or chlor-amphenicol administration is corrected by prednisolone. Rats treated with acetoxycycloheximide respond to 1-norepinephrine with normally vigorous blood pressure elevation suggesting that phasic contractile proteins remain intact.

EXPERIMENTAL STUDY ON THE BLOOD PRESSURE OF PREGNANT HYPERTENSIVE RATS. II. THE MECHANISM OF THE FALL OF BLOOD PRESSURE AT LATE PREGNANCY IN EXPERIMENTALLY HYPERTENSIVE RATS.

The mechanism of the fall of blood pressure during pregnancy in experimentally hypertensive rats was studied in this report. 1. Fetal ablation carried out on the 16th day of pregnancy without damage to the placenta interfered with the fall of blood pressure in hypertensive rats with renal infarction. 2. Intraperitoneal transplantation of new born kidney, liver, spleen or placenta as cell suspension or parenteral injection of placental homogenate to renal hypertensive rats was per-formed and the changes of blood pressure by these procedures were studied. In these studies, only new born kidney transplantation led to a definite fall of blood pressure. Histologically the viable epithelial cells of new born kidney assumed a tubular structure or irregular cluster in the peritoneal granule or lymphnode. 3. Judging from these data, the fetus kidneys may play an important role in the fall of blood pressure at late pregnancy in experimentally and spontaneously hypertensive rats, that is, the fetus kidney may secrete some antihypertensive substances which can lower the blood pressure of pregnant hypertensive rat.

Effect of gamma-aminobutyric acid (GABA) on normotensive or hypertensive rats and men.

1. The effect of GABA on blood pressure of normotensive and hypertensive rats or men was investigated.2. GABA, when administered orally one g per day for a month, did not cause any appreciable changes in body weight, blood pressure and other side effects in normotensive rats. No histological changes were found in their organs.3. On the contrary, GABA reduced the elevated blood pressure of experimental renal hypertensive rats at the doses of more than thirty mg per day. Its effect was maintained during the application, and disappeared within one week after the interruption of treatment.4. When glutamate or aspartic acid of 50 mg per day was orally applied for three weeks, no change was observed in blood pressure of hypertensive rats.5. GABA, administered subcutaneously was also more effective in hypertensive rats than in normotensive ones.6. Subcutaneous injections of GABA (1-3 mg per kg) on normotensive subjects produced slight uncomfortable side effects.7. GABA, if administered orally three g per day, did not cause any appreciable effects on normotensive persons, but it lowered remarkably the elevated blood pressure of patients.

Relation of saluretic and hypotensive effects of hydrochlorothiazide in the rat.

Hydrochlorothiazide causes a marked loss of Na and of water in both fully alimented rats and in rats deprived of food and/or water. The increased urinary volume corresponds closely to the shrinkage of the extracellular fluid volume (inulin space) but the decrease in extracellular Na is not sufficient to account for the Na excretion, suggesting that Na is withdrawn from cells and perhaps bone stores as well. The fall in blood pressure in hypertensive rats is not due to simple shrinkage of the extracellular space and plasma volume, but can be referred to the rise in Na gradient induced by withdrawal of cell sodium.

Effect of cortisone on blood pressure of hypertensive rats deprived of dietary potassium.

ArticleEffect of Cortisone on Blood Pressure of Hypertensive Rats Deprived of Dietary PotassiumRay H. Rosenman, S. Charles Freed, and M. K. SmithRay H. RosenmanFrom the Harold Brunn Institute, Mount Zion Hospital, San Francisco, California, S. Charles FreedFrom the Harold Brunn Institute, Mount Zion Hospital, San Francisco, California, and M. K. SmithFrom the Harold Brunn Institute, Mount Zion Hospital, San Francisco, CaliforniaPublished Online:01 May 1954https://doi.org/10.1152/ajplegacy.1954.177.2.325MoreSectionsPDF (866 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformationCited ByHypertonieHypertonieThe alkali metal ions in the organism More from this issue > Volume 177Issue 2May 1954Pages 325-329 Copyright & PermissionsCopyright © 1954 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1954.177.2.325PubMed13158569History Received 11 October 1953 Published online 1 May 1954 Published in print 1 May 1954 Metrics

Effect of varying dietary potassium upon the blood pressure of hypertensive rats.

Effect of varying dietary potassium upon the blood pressure of hypertensive rats.

Depressor effect of potassium deprivation on the blood pressure of hypertensive rats.

ArticleDepressor Effect of Potassium Deprivation on the Blood Pressure of Hypertensive RatsMeyer Friedman, Ray H. Rosenman, and S. Charles FreedMeyer FriedmanFrom the Mount Zion Hospital, Harold Brunn Institute for Cardiovascular Research San Francisco, California, Ray H. RosenmanFrom the Mount Zion Hospital, Harold Brunn Institute for Cardiovascular Research San Francisco, California, and S. Charles FreedFrom the Mount Zion Hospital, Harold Brunn Institute for Cardiovascular Research San Francisco, CaliforniaPublished Online:31 Oct 1951https://doi.org/10.1152/ajplegacy.1951.167.2.457MoreSectionsPDF (768 KB)Download PDF ToolsExport citationAdd to favoritesGet permissionsTrack citations ShareShare onFacebookTwitterLinkedInWeChat Previous Back to Top Next Download PDF FiguresReferencesRelatedInformation More from this issue > Volume 167Issue 2October 1951Pages 457-461 Copyright & PermissionsCopyright © 1951 by American Physiological Societyhttps://doi.org/10.1152/ajplegacy.1951.167.2.457PubMed14894673History Received 12 July 1951 Published online 31 October 1951 Published in print 31 October 1951 Metrics

Observations of influence of corn-silk extract (Stigmata maydis zeae) on blood pressure in hypertensive rats: Wastl, H.: Arch. Internat. de pharmacodyn. et de thérap. 74:1 (April), 1947

Observations of influence of corn-silk extract (Stigmata maydis zeae) on blood pressure in hypertensive rats: Wastl, H.: Arch. Internat. de pharmacodyn. et de thérap. 74:1 (April), 1947

Influence of two thiourea derivatives on blood pressure in hypertensive rats: Wastl, H.: Arch. internat. de pharmacodyn, et de thérap. 71: 204, (Dec. 31), 1945

Influence of two thiourea derivatives on blood pressure in hypertensive rats: Wastl, H.: Arch. internat. de pharmacodyn, et de thérap. 71: 204, (Dec. 31), 1945

Purification and bioassay of tissue extracts capable of lowering the blood pressure of hypertensive rats: Remington, J. W., Cartland, G. F., Drill, V. A., and Swingle, W. W.: Am. J. Physiol. 140: 627, 1944

Purification and bioassay of tissue extracts capable of lowering the blood pressure of hypertensive rats: Remington, J. W., Cartland, G. F., Drill, V. A., and Swingle, W. W.: Am. J. Physiol. 140: 627, 1944

Influence of Vitamin K Preparations on Blood Pressure in Hypertensive Rats.

SummaryVitamin K produces lowering of blood pressure in rats rendered hypertensive (by silk perinephritis. The hydroquinone compound Synkayvite shows no such effect. The trial of vitamin K in human hypertension is being considered.