Plasma renin activity during exercise in the dog

M. D. Lifschitz, L. D. Horwitz

Research output: Contribution to journalArticlepeer-review

4 Scopus citations

Abstract

Previous workers have suggested that a rise in plasma renin activity (PRA) may mediate some of the hemodynamic changes associated with exercise. To test this hypothesis in nine dogs chronically instrumented for measurement of aortic pressure (catheter) or cardiac output (ascending aorta electromagnetic flow probe) PRA was measured by radioimmunoassay in blood samples drawn before and during running on a level treadmill at 4-8 miles per hour. Exercise caused increases in heart rate from 96±5 (SE) to 186±7 beats/min, cardiac output from 2.8±0.3 to 6.2±0.6 liters/min, and mean aortic pressure from 115±5 to 132±5 mm Hg (P<0.01). Mean PRA was 6.6±0.7 (SE) ng of angiotensin 1/ml per 3 hours before and 7.6±1.2 ng Ang I during exercise, values that are not different statistically. Propranolol reduced PRA at rest from 8.6±1.1 to 5.9±1.1 ng Ang I (P<0.05), but there was no significant difference between resting and exercise levels, although the increments in heart rate, cardiac output, and mean aortic pressure were reduced. Standing on hindlimbs for 5 minutes did not cause a change in mean aortic pressure or PRA. However, administration of pentolinium reduced mean aortic pressure, and PRA rose from 6.0±1.1 to 9.8±1.5 ng Ang I. Exercise, with or without β adrenergic blockade, does not cause increased PRA in conscious dogs in which the renin angiotensin system is normally responsive.

Original languageEnglish (US)
Pages (from-to)483-487
Number of pages5
JournalCirculation research
Volume38
Issue number6
DOIs
StatePublished - 1976

ASJC Scopus subject areas

  • Physiology
  • Cardiology and Cardiovascular Medicine

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