RT Journal Article
SR Electronic
T1 EFFECTS OF SYMPATHETIC AND CENTRAL NERYOUS SYSTEM ALTERATIONS ON THE BLOOD PRESSURE RESPONSES TO PHENTOLAMINE
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 743
OP 747
VO 180
IS 3
A1 CLIFFORD C. HILLIARD
A1 ERVIN E. BAGWELL
A1 HERMAN B. DANIELL
YR 1972
UL http://jpet.aspetjournals.org/content/180/3/743.abstract
AB An injection of phentolamine (5 mg/kg) in 13 control animals resulted in increases in myocardial contractile force and heart rate with a simultaneous decrease in aortic blood pressure. If the sympathetic efferent system is blocked by reserpine, ganglionic blockade, spinal anesthesia or C1 spinal section, phentolamine elicits an augmentation of aortic blood pressure. This is not due to a positive inotropic effect since heart force actually decreases. The pressor effect is not mediated by alpha receptors since prior blockade does not abolish the pressor effect. If the action of phentolamine is limited to the circulation of the head, a peripheral depressor response is observed. The data indicate that phentolamine appears to produce direct vasoconstriction in the absence of sympathetic tone. Phentolamine also appears to stimulate central hypotensive centers which in conjunction with intrinsic alpha blockade produces precipitous decreases in aortic blood pressure. The combination of these last two effects masks the direct vasoconstriction in normal animals. © 1972 by The Williams & Wilkins Co.