Journal of Applied Physiology, Vol 71, Issue 5 1843-1847, Copyright © 1991 by American Physiological Society
Effects of environmental temperature on the venodilatory response to nitroglycerin
J. A. Gascho, D. Gehman and R. Brandt
Division of Cardiology, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
The venodilatory response to nitroglycerin (0.8 mg sublingually) was
measured in 10 healthy young male volunteers in a cool [24.3 +/- 0.6
degrees C skin temperature (Tsk)] and a warm environment (34.7 +/- 0.2
degrees C Tsk). Nitroglycerin caused mean arterial pressure to fall and
heart rate to rise in both the cool (105 +/- 2 to 96 +/- 3 mmHg; 55 +/- 3
to 62 +/- 3 beats/min) and the warm environment (87 +/- 3 to 81 +/- 3 mmHg;
66 +/- 4 to 75 +/- 3 beats/min), but the fall in pressure was greater in
the cool than in the warm environment. Forearm blood flow was reduced and
forearm vascular resistance elevated in the cool (117 +/- 19 units; 1.15
+/- 0.08 ml.100 cc arm-1.min-1) compared with the warm environment (15 +/-
3 units; 8.60 +/- 1.89 ml.100 cc arm-1.min-1). Nitroglycerin caused forearm
vascular resistance to fall in the cool but had no effect in the warm
environment. Venous distensibility (increase in venous volume per 30-mmHg
increase in venous pressure) was twice as great in the warm as in the cool
environment (3.90 +/- 0.27 vs. 1.88 +/- 0.23 ml/100 cc arm). However, the
venodilatory effect of nitroglycerin was similar in the cool and warm
environments (0.79 +/- 0.10 vs. 0.67 +/- 0.13 ml/100 cc arm, respectively).
Arterioles are not dilated by nitroglycerin in the warmer environment, but
the venodilatory effect of nitroglycerin is quantitatively similar in the
two environments.
