[Effects of intracisternal injection of naloxone on the depressor response to stimulation of renal afferent nerve in rabbits].
The purpose of this study was to observe the effects of opioid receptor and alpha-adrenergic receptors in the lower brain stem on the depressor response to electrical stimulation of renal afferent nerve, using intracisternal injection of blockers of these receptors. Experiments were conducted in sodium pentobarbital-anesthetized rabbits. The intracisternal injection (ict) of artificial cerebrospinal fluid (CSF) did not greatly affect the depressor response to stimulation of renal afferent nerve (RAS) and of aortic nerve (ANS). Ict of 550 nmol naloxone significantly inhibited the depressor response to RAS (P less than 0.05) but enhanced the depressor response to ANS (P less than 0.05). Ict of 335 nmol phentolamine significantly inhibited the depressor response to both RAS and ANS. Ict of naloxone reversed the phentolamine inhibition of the depressor response to ANS but did not affect the phentolamine inhibition of the depressor response to RAS. Ict of both naloxone and phentolamine did not affect the inhibitory interaction between the RAS-induced depressor and aortic baroreflex. Ict of phentolamine significantly decreased MAP, and ict of naloxone did not decrease MAP but reversed the decrease in MAP by ict of phentolamine. These data suggest that the activation of opioid receptors in the lower brain stem enhances the depressor response to RAS and attenuates the depressor response to ANS. Moreover, activation of alpha-adrenergic receptors in the lower brain stem facilitates the depressor response to RAS and ANS.
Pan
J Y
JY
Pan
W X
WX
Chen
Y H
YH
Zhan
C Y
CY
D000818:Animals; D001011:Aorta / Q000294:innervation; D001794:Blood Pressure / Q000187:drug effects*; D001933:Brain Stem / Q000502:physiology; D005260:Female; D007278:Injections, Spinal; D007668:Kidney / Q000294:innervation*; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D009412:Nerve Fibers / Q000502:physiology; D011817:Rabbits; D011957:Receptors, Opioid / Q000502:physiology
D011957:Receptors, Opioid; D009270:Naloxone