AJP - Heart and Circulatory Physiology, Vol 250, Issue 1 76-H81, Copyright © 1986 by American Physiological Society
Augmented catecholamine uptake by the heart during hemorrhage in the conscious dog
O. L. Woodman, J. Amano, T. H. Hintze and S. F. Vatner
Changes in arterial and coronary sinus concentrations of norepinephrine
(NE) and epinephrine (E) in response to hemorrhage were examined in
conscious dogs. Hemorrhage (45 +/- 3.2 ml/kg) decreased mean arterial
pressure by 47 +/- 6%, left ventricular (LV) dP/dt by 38 +/- 6%, and mean
left circumflex coronary blood flow by 47 +/- 6%, while heart rate
increased by 44 +/- 13%. Increases in concentrations of arterial NE (5,050
+/- 1,080 from 190 +/- 20 pg/ml) and E (12,700 +/- 3,280 from 110 +/- 20
pg/ml) were far greater than increases in coronary sinus NE (1,700 +/- 780
from 270 +/- 50 pg/ml) and E (4,300 +/- 2,590 from 90 +/- 10 pg/ml). Net
release of NE from the heart at rest was converted to a fractional
extraction of 66 +/- 9% after hemorrhage. Fractional extraction of E
increased from 16 +/- 6% at rest to 73 +/- 8% after hemorrhage. In
cardiac-denervated dogs, hemorrhage (46 +/- 2.8 ml/kg) decreased mean
arterial pressure by 39 +/- 15%, LV dP/dt by 36 +/- 10%, and mean left
circumflex coronary blood flow by 36 +/- 13%, while heart rate increased by
24 +/- 10%. Hemorrhage increased arterial NE (1,740 +/- 150 from 210 +/- 30
pg/ml) and E (3,050 +/- 880 from 140 +/- 20 pg/ml) more than it increased
coronary sinus NE (460 +/- 50 from 150 +/- 30 pg/ml) and E (660 +/- 160
from 90 +/- 20 pg/ml) but significantly less (P less than 0.05) than
observed in intact dogs. These experiments indicate that hemorrhage, unlike
exercise and sympathetic nerve stimulation, does not induce net overflow of
NE from the heart.(ABSTRACT TRUNCATED AT 250 WORDS)
