Effects of nitroglycerin on cardiac function and regional blood flow distribution in conscious dogs

1978 ◽  
Vol 234 (3) ◽  
pp. H244-H252 ◽  
Author(s):  
S. F. Vatner ◽  
M. Pagani ◽  
J. D. Rutherford ◽  
R. W. Millard ◽  
W. T. Manders
Keyword(s):  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Left Ventricular ◽  
Conscious Dogs ◽  
Blood Flow Distribution ◽  
Biphasic Response ◽  
Cardiac Work ◽  
Regional Hemodynamics ◽  
Arteriolar Vasodilation

The effects of intravenous infusion of nitroglycerin (NTG), 8 and 32 microgram/kg.min for 7 min, and of sublingual NTG, 1.2 mg, were examined on direct and continuous measurements of systemic, coronary, and regional hemodynamics, left ventricular (LV) dimensions, pressures, and myocardial contractility in conscious dogs. NTG induced sustained reductions in LV dimensions and transient increases in heart rate and dP/dt, and decreases in mean arterial pressure. Initially NTG increased cardiac output and flows to the coronary, mesenteric, renal, and iliac beds, while systemic and regional vascular resistances fell. Later, cardiac output, cardiac work, and mesenteric and iliac flows fell significantly below control, and significant vasoconstriction in the systemic as well as mesenteric, iliac, and coronary beds was observed at a time when LV end-diastolic dimensions were still significantly reduced. Peripheral vasoconstriction was not observed with systemic NTG in deafferented dogs or when NTG, 1 microgram/kg.min, was infused intra-arterially into the iliac bed. Thus, systemic NTG induces a biphasic response consisting of initial arteriolar vasodilation followed by vasoconstriction in the mesenteric, iliac, coronary and systemic beds, which is presumably due to longer lasting effects on preload and to secondary reflex responses to the drug.

Left ventricular cannulation for microsphere estimation of rabbit renal blood flow

1980 ◽  
Vol 238 (5) ◽  
pp. H736-H739 ◽  
Author(s):  
J. Bhattacharya ◽  
L. J. Beilin
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Renal Blood Flow ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Left Ventricular ◽  
Blood Flow Distribution ◽  
Per Se ◽  
Conscious Animals ◽  
Renal Blood Flow Distribution

When cannulation of the left ventricle and the left atrium were compared as methods for measuring for measuring renal blood flow distribution with radioactive microspheres in 9 conscious and 6 anesthetized rabbits, there were no differences between the two injection routes. Left ventricular cannulation per se did not affect cardiac output, nor the percentage of the cardiac output supplying the kidneys; but cardiac outputs estimated by thermodilution by injections via this route were up to 10% greater than those from left atrial injection. The advantages of left ventricular cannulation for experiments on regional blood flow distribution in conscious animals are discussed.

Effects of angiotensin, vasopressin, and methoxamine on cardiac function and blood flow distribution in conscious dogs

1976 ◽  
Vol 231 (5) ◽  
pp. 1579-1587 ◽  
Author(s):  
GR Heyndrickx ◽  
DH Boettcher ◽  
SF Vatner
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Left Ventricular ◽  
Blood Flow Distribution ◽  
Cardiac Rate ◽  
Differential Effects ◽  
Differential Pattern

A comparison was made of the effects of vasopressin (ADH), methoxamine (MX), and angiotensin II (AN) on coronary and left ventricular dynamics, cardiac output, and regional blood flow distribution in intact, consci9us dogs. At an equal percent pressure elevation, ADH reduced cardiac output and cardiac rate the most, while AN had the least effect. After denervation of arterial baroreceptors, ADH still reduced heart rate, while AN increased it, suggesting nonbaroreceptor negative and positive chronotropic effects, respectively. A differential pattern on peak dP/dt was also observed, with ACH causing a greater reduction than MX while AN did not decrease dP/dt. With heart rate held constant, AN did not reduce dP/dt, suggesting a direct positive inotropic effect since dP/dt should have fallen slightly due to reflex mechanisms, as was observed with MX and ADH. ADH induced the greatest increase in coronary resistance (140%), while the least (46%) was observed with AN, which could be explained, in part, by the differential effects observed on cardiac rate and contractility. The greatest increase in resistance in the iliac bed occurred with ADH (30%), and the least with AN (34%). Conversely, the greatest constriction in the renal bed occurred with AN (95%), and lesser amounts were observed with ADH (36%) and MX (35%). Thus ADH, MX, and AN exert potent yet differential vasoconstricting actions on peripheral beds. In addition, while all three agents elicited coronary vasoconstriction, the differential effects on coronary vascular resistance appeared to be due predominantly to a difference in chronotropic and inotropic actions.

Intravenous infusion of nitroglycerin: effects upon cardiovascular dynamics and regional blood flow distribution in conscious dogs

1982 ◽  
Vol 60 (12) ◽  
pp. 1436-1443 ◽  
Author(s):  
Louis Dumont ◽  
Claudette Lamoureux ◽  
Jacques Lelorier ◽  
Paul Stanley ◽  
Claude Chartrand
Keyword(s):  
Blood Flow ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Blood Perfusion ◽  
Left Ventricular ◽  
Conscious Dogs ◽  
Blood Flow Distribution ◽  
Hemodynamic Changes ◽  
Before And After ◽  
Local Reflex

We have studied both central and peripheral hemodynamic changes induced by infusion of nitroglycerin (55 μg/kg per minute) over a 15-min period in conscious dogs to clarify its mechanism of action. Dogs were prepared with an electromagnetic flow probe positioned at the root of the aorta, and microspheres (9 μm) were used to measure regional blood flow distribution before and after 15 min of infusion. Controlled hypotension (−15 to −20 mmHg (1 mmHg = 133.322 Pa)) was maintained throughout the infusion period and this hypotensive state was associated with a significant decrease in stroke volume (−30%), cardiac index (−20%), and left ventricular work (−43%). Regional blood flow studies showed that at the 15th min of infusion, nitroglycerin induced significant decrease in blood flow to all components of the myocardium (range −12 to −20%) while their vascular resistances were not affected significantly. Blood perfusion to liver (hepatic artery), spleen, and intestine was also modified significantly (−22, −18, and −16%, respectively) while their vascular resistances remained close to control values. By the time measurements were made, blood flow and vascular resistance of cerebral and renal tissues remained normal. For each organ studied, blood perfusion was uniform. These results indicate that nitroglycerin elicits both central and peripheral hemodynamic changes and that local reflex adjustments modify the vasodilator effect of the drug in most vascular beds that we have studied.

Regional blood flow distribution during the Cushing response: alterations with adrenergic blockade

1985 ◽  
Vol 248 (1) ◽  
pp. H98-H108
Author(s):  
D. G. van Wylen ◽  
L. G. D'Alecy
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Peripheral Tissue ◽  
Systemic Hypertension ◽  
Tissue Blood Flow ◽  
Blood Flow Distribution ◽  
Beta Receptor ◽  
Cushing Response

Regional blood flow distribution (microspheres) and cardiac output (CO, thermal dilution) were measured during the Cushing response in unblocked (UB), beta-receptor-blocked (BB, 2 mg/kg propranolol iv), or alpha-receptor blocked (AB, 0.5 mg/kg + 0.5 mg X kg-1 X min-1 phentolamine iv) chloralose-anesthetized dogs. Intracranial pressure was increased to 150 mmHg by infusion of temperature-controlled artificial cerebrospinal fluid into the cisterna magna. Similar increases in mean arterial pressure were seen in UB and BB, but in AB a Cushing response could not be sustained. In UB, cerebral blood flow (CBF) decreased 50%, coronary blood flow (CoBF) increased 120%, and peripheral tissue blood flow was reduced only in the kidneys (18%) and the intestines (small 22%, large 35%). Blood flow to the other viscera, skin, and skeletal muscle was unchanged. CO (16%) and heart rate (HR, 38%) decreased, and total peripheral resistance (TPR, 68%) and stroke volume (SV, 38%) increased. In BB, CBF decreased 50%, CoBF decreased 20%, and blood flow was reduced 40-80% in all peripheral tissues. CO (69%) and HR (62%) decreased, TPR increased 366%, and SV was unchanged. We conclude that the Cushing response in UB animals combines an alpha-receptor-mediated vasoconstriction with a beta-receptor cardiac stimulation. The beta-mechanism is neither necessary nor sufficient for the hypertension. However, the combination of alpha- and beta-adrenergic mechanisms maintains cardiac output and peripheral tissue blood flow relatively constant while producing a systemic hypertension.

Control of cardiac output by regional blood flow distribution

1974 ◽  
Vol 2 (2) ◽  
pp. 149-163 ◽  
Author(s):  
Thomas G. Coleman ◽  
R. Davis Manning ◽  
Roger A. Norman ◽  
Arthur C. Guyton
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Regional Blood Flow ◽  
Flow Distribution ◽  
Blood Flow Distribution
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