摘要:

Hypersecretion of aldosterone occurred at the onset of signs of congestive heart failure in a large series of dogs with a large infrarenal aortic-caval fistula. There was evidence of right heart failure in all animals and in four of the dogs râles or frank pulmonary edema was present. Marked sodium retention and ascites or edema were consistent findings and in the majority of the animals central venous pressure was elevated.Hypophysectomy was followed by a striking fall in both aldosterone and corticosterone secretion but in several animals hypersecretion of aldosterone was evident in the absence of the anterior pituitary. Subsequent acute bilateral nephrectomy of these hypophysectomized dogs resulted in a marked drop of aldosterone secretion to a very low level, and a precipitous fall in arterial pressure frequently occurred. An intravenous infusion of a saline extract of each animal's kidneys produced a striking elevation in aldosterone output; corticosterone secretion and arterial pressure increased consistently. The kidneys of these dogs with heart failure secondary to an A-V fistula frequently showed hypergranulation and hyperplasia of the juxtaglomerular cells. The present findings suggest that the increased rate of aldosterone secretion was mediated by the renin-angiotensin system.Measurements of arterial pressure and renal hemodynamic function demonstrated a fall of mean renal arterial pressure, glomerular filtration rate, and renal plasma flow, whereas arterial pulse pressure above the fistula and presumably in the kidneys was increased. The data suggest that decreased pulse pressure is unnecessary for activation of the renal mechanism leading to hyperaldosteronism.

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

摘要:

1. In normal rabbits, single intravenous doses ofE. coliandSalmonellaendotoxin produce an immediate, transient, hypercoagulable state. Venous stasis occurring during such a state allows the formation of massive red thrombi at sites of obstructed blood flow. The duration of stasis required to produce thrombi following endotoxin administration depends in part on the preinfusion silicone clotting time of the rabbit.2.E. coliendotoxin shortens the recalcification time of platelet-poor plasma obtained from normal subjects and from patients with heredofamilial coagulation defects of Factor XII (Hageman) and Factor IX (plasma thromboplastin component). In contrast, the recalcification time of platelet-poor plasma obtained from patients with Factor XI (plasma thromboplastin antecedent) deficiency is lengthened by endotoxin. It is suggested that the heat-labile plasma factor known to be required for the platelet-endotoxin interaction may be related to Factor XI.

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

摘要:

Vascular reactivity was examined in vessels of the perfused hindquarters of alloxan diabetic and control rats. A significant increase was noted in responsiveness of the diabetic animals to intra-arterial injection of epinephrine, norepinephrine, and synthetic angiotensin. No difference was observed in the vasoconstrictor effects of lumbar sympathetic nerve stimulation or intra-arterial administration of tyramine. Results obtained in diabetic animals were compared with those in animals treated with reserpine. It was found that the reserpinized animals exhibited increased vascular responsiveness only to the catecholamines, and not to angiotensin, vasopressin, tyramine, or barium chloride. Whereas the vascular smooth muscle of diabetic rats was sensitized to epinephrine and norepinephrine, isolated atria from these animals responded normally to the catecholamines. The 24-hour urinary excretion of the catecholamines was significantly elevated in diabetic animals. The data suggest that enhanced vascular reactivity seen in diabetic rats does not result from neuropathy of the sympathetic nervous system. The possible contributions of factors including alloxan per se and body weight to development of increased vascular reactivity in diabetes were considered, but the mechanism for the increase in vascular responsiveness remains unidentified.

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

摘要:

Effects of stimulation of the cardiac sympathetic nerves and intravenous administration of sympathomimetic amines on the multiple response or fibrillation threshold (VMRT) and on other properties of the dog ventricles were compared. Stimulation of the cardiac sympathetic nerves decreased the VMRT. Administration of sympathomimetic amines caused a brief decrease in the VMRT followed by a sustained increase. Temporal dispersion of recovery of excitability and the degree of ventricular vulnerability were closely related; the ventricle was more vulnerable to fibrillation when the dispersion was increased. The hyperkalemic effect of epinephrine was not responsible for the observed changes in ventricular vulnerability.

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

摘要:

The intra-arterial administration of vasodilator drugs (acetylcholine, histamine, isoproterenol, adenosine triphosphate, bradykinin, and isoxsuprine hydrochloride) induced reversible depression in the maximal contractile force of the intermittently stimulated gastrocnemius-soleus muscles in the cat. In general, blood flow to the muscles was held constant and perfusion pressure was observed. The agents were effective in depressing the muscle at doses the same as those required to produce dilatation in the resting muscle. Increase in blood flow during infusion could reverse the depression. Atropine, in amounts sufficient to block the hypotensive action of intravenously administered acetylcholine, prevented the muscle depressant action of the latter, while leaving unaffected the action of histamine.Further experiments, utilizing mainly acetylcholine as the prototype, were performed to test the hypothesis that the depressant effect on the gastrocnemius was closely related to a vascular action of the drugs. Evidence serving both to exclude neuromuscular blockade and to support a vascular effect was adduced from three sets of observations. 1) In vitro tests of blocking action of acetylcholine and histamine on nerve-muscle preparations indicated that any such action would require doses several hundred times greater than those effective in the cat gastrocnemius. 2) Under conditions where dependency of contractile force on blood flow varied, comparison of the effects of acetylcholine tod-tubocurarine and decamethonium on the cat gastrocnemius showed that when dependency on flow was reduced the effect of acetylcholine was also, while neuromuscular blockade was affected little. 3) A decrease occurred in the I131clearance rate from the gastrocnemius parallel to the reduction in muscle force from acetylcholine, while a much smaller, or delayed, reduction in rate occurred when force was reduced equally byd-tuboeurarine.A redistribution of blood flow within the muscle and associated connective tissue may account for the results.

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

摘要:

Instantaneous and continuous shearing strains at various sites in the wall of the left ventricle were measured in 19 dogs with a specially designed transducer. Relatively large shearing strains occurred during the “isovolumic” and immediately prediastolic portions of systole. Shearing strain during diastole was small. Under control conditions the average shearing strain during the ejection period of systole was 0.0218 radians (1.25°) at a 6 mm depth into the myocardium. Intravenous infusion of norepinephrine (approximately 0.001 mg/kg per minute) increased myocardial shear from 0.0177 radians (1.01°) to 0.0274 radians (1.57°) during the ejection period.It is concluded that shearing strain in the myocardium during the ejection period is relatively small.

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

摘要:

The instantaneous and continuous thickness of the left ventricular wall was measured in ten dogs with a specially designed transducer. The thickness change during the “isovolumic” phase of systole was 11%. The average thickness increased an additional 10% during the ejection period of systole. These average values increased to 20% and 15% respectively with the administration of norepinephrine (approximately 0.001 mg/kg per minute).Transverse and longitudinal epicardial are strains were compared with thickness strain of the myocardium. Assuming the myocardium is incompressible, reasonable agreement was found in the three strains, which lends support to the measurements that were made.It is concluded that changes in the thickness of the myocardial wall during the cardiac cycle may be important in some considerations of the heart's performance.

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

摘要:

Pairs of sheep were connected via a unilateral carotid-jugular anastomosis in fourteen experiments. With the cross circulation open, pulmonary embolism induced in the donor sheep produced a rise in pulmonary arterial pressure, a fall in lung compliance, and an increase in ventilation in the recipient animal. The transmitted effects were more pronounced with barium sulfate lung embolism than with blood clot lung embolism.These observations are consistent with the assumption that in acute experimental lung embolism a humoral agent is being released causing constriction of the lung vessels and airways.

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID

ISSN:0009-7330    

出版商:OVID    

年代:1964

数据来源: OVID