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Effects of altered autonomic control on left ventricular function in conscious dogs
Journal article   Peer reviewed

Effects of altered autonomic control on left ventricular function in conscious dogs

Vernon S Bishop and Lawrence D Horwitz
The American journal of physiology, Vol.221(5), pp.1278-1282
11/1971
DOI: 10.1152/ajplegacy.1971.221.5.1278
PMID: 4399395

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Abstract

In eight conscious dogs, effects of beta-adrenergic, vagal, and combined beta-adrenergic and vagal blockage on left ventricular internal diameter, pressure, and outflow were measured at rest and during acute volume loading. At rest, beta-adrenergic blockage resulted in a decrease in heart rate with no change in stroke volume but increased end-diastolic and end-systolic diameters, whereas vagal blockage resulted in an elevated heart rate with reductions in stroke volume, end-diastolic, and end-systolic diameters. Combined blockage, at rest, was associated with elevations in heart rate, diminished stroke volume, and increases in end-diastolic and end-systolic diameters. During acute volume loading, beta-adrenergic blockage reduced peak heart rate and stroke volume, and elevated end-systolic diameter, whereas vagal blockage, despite an elevated heart rate, did not alter peak stroke volume and reduced end-diastolic diameter. The response to acute volume loading in combined blockage was characterized by reduction in peak stroke volume and end-diastolic diameter. Stroke volume was found to be dependent not only on the initial fiber length but also on the sympathetic innervation. This was demonstrated by the increase in end-systolic diameter following beta-adrenergic blockage.

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