AJP - Heart and Circulatory Physiology, Vol 250, Issue 4 600-H605, Copyright © 1986 by American Physiological Society
Antihypertensive effect of thyroidectomy in SHR: associated changes in heart performance
R. L. Rodgers and J. H. McNeill
Effects of thyroidectomy (TX; 10 wk) on the performance of perfused hearts
from spontaneously hypertensive rats (SHR) were compared with effects on
hearts from normotensive Wistar-Kyoto (WKY) controls. TX prevented the
development of hypertension in SHR and moderately reduced arterial pressure
of WKY, confirming previous observations. TX also reduced
heart-to-body-weight ratio (relative left ventricular hypertrophy) but not
left-to-right ventricular weight ratio (absolute hypertrophy) of SHR. The
performances of euthyroid SHR and WKY hearts were similar to each other. TX
reduced maximum left ventricular pulse pressure to the same extent in both
strains and had no effect on hydraulic work, O2 consumption, or efficiency
of contraction in either strain. However, TX reduced maximum left
ventricular +dP/dt of SHR but not of WKY hearts. The results show that
hypothyroidism selectively depresses the contractility (LV +dP/dt) of SHR
hearts but otherwise has similar effects on the performance of hypertensive
and normotensive rat hearts.
