AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 4 655-R662, Copyright © 1984 by American Physiological Society
Participation of central alpha-receptors on hemodynamic response to E. coli endotoxin
S. Koyama
The time course of changes in mean blood pressure (MBP), heart rate (HR),
and renal blood flow (RBF) in a control group of anesthetized dogs given
only endotoxin (1 mg/kg iv) was compared with groups pretreated with
alpha-antagonists either intravenously or intracisternally (ic). The
decreases in MBP and RBF in the control group were abolished by
intracisternal prazosin (0.1 mg/kg ic). MBP response to endotoxin after
intravenous prazosin did not differ from that of the control group;
however, the endotoxin-induced decrease in RBF after intravenous prazosin
was significantly greater than that in the control group. HR responses to
endotoxin were not altered by either intracisternal or intravenous
prazosin. MBP and RBF responses to endotoxin after intravenous or
intracisternal yohimbine (0.5 mg/kg iv or ic) did not differ from the
control responses. However, significant differences occurred in the time
course of changes in HR only when yohimbine was administered
intracisternally. These observations suggest that the hypotensive effect
and reduction of RBF due to endotoxin may be mediated by alpha
1-adrenoceptors at least in the central nervous system and that of HR
response may be mediated alpha 2-adrenoceptors.
