[Role of central vasopressin in the maintenance of cardiovascular activities during acute hypoxia].
To investigate whether central vasopressin play a role in the maintenance of cardiovascular activities of rats exposed to acute hypoxia, blood pressure, heart rate, pressures of left and right ventricles and their dp/dt were monitored in rats anesthetized with urethane. The rats were divided into three groups, each of which received intracerebroventricular injection (icv.) of V1- and V2-vasopressinergic antagonists (4 micrograms, each) and equivolumetric vehicle (8 microliters, served as control group). Ten min after icv. three groups of rats were exposed to acute hypoxia (9% O2 in N2) for 15 min before reoxygenation. During hypoxia, MBP, HR, LVSP and LV + dp/dtmax of V1-antagonist treated group decreased more significantly than those of the control group (P < 0.01). After reoxygenation there were no significant differences between both groups. V1-antagonist and the vehicle had no detectable effect on the cardiovascular parameters during normoxia. Although icv. V2-antagonist caused a transient augmentations of HR, MBP, LVSP and LV + dp/dtmax except for RVSP and RV + dp/dtmax, there were no significant differences in cardiovascular activities between V2-antagonist treated group and control group during hypoxia and reoxygenation. These results indicate that central endogenous vasopressin play an important role in the maintenance of cardiovascular activities during hypoxia via its V1-receptor without involving V2-receptor. The central vasopressin does not have a tonic effect on cardiovascular activities under normal conditions.
Xiao
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Shanghai Institute of Physiology, Academia Sinica.
Zhou
Z N
ZN
D000818:Animals; D065092:Antidiuretic Hormone Receptor Antagonists; D001794:Blood Pressure; D006339:Heart Rate; D000860:Hypoxia / Q000503:physiopathology*; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D014667:Vasopressins / Q000494:pharmacology / Q000502:physiology*
D065092:Antidiuretic Hormone Receptor Antagonists; D014667:Vasopressins