Reversal by pertussis toxin and N-ethylmaleimide of the facilitation of baroreceptor reflex response by somatostatin in the rat.
We evaluated the transmembrane signaling mechanism that may underlie the facilitatory action of somatostatin (SOM) on baroreceptor reflex (BRR), using adult, male, Sprague-Dawley rats anesthetized with pentobarbital sodium (40 mg/kg, i.p.). Intracerebroventricular (i.c.v.) application of SOM (2 nmol) promoted a significant elevation in BRR response, induced by phenylephrine (5 micrograms/kg, i.v.). This potentiatory action of the tetradecapeptide was significantly reversed after pretreating animals with bilateral microinjection of pertussis toxin (25 ng) or N-ethylmaleimide (2 nmol) into the nucleus tractus solitarius (NTS), the terminal site for baroreceptor afferents. These results suggest that a pertussis toxin-sensitive GTP-binding regulatory protein, possibly Gi, may be involved in the modulation of the BRR by SOM at the NTS.
Department of Medical Research, Veterans General Hospital-Taipei, Taiwan, Republic of China.
J Y
JY
Chan
S S
SS
Lin
S H
SH
Chan
D000344:Afferent Pathways / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D005033:Ethylmaleimide / Q000008:administration & dosage / Q000494:pharmacology*; D006339:Heart Rate / Q000187:drug effects*; D007275:Injections, Intravenous; D007276:Injections, Intraventricular; D008297:Male; D008526:Medulla Oblongata / Q000187:drug effects / Q000502:physiology*; D008845:Microinjections; D037342:Pertussis Toxin; D010656:Phenylephrine / Q000008:administration & dosage / Q000494:pharmacology; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D012018:Reflex / Q000187:drug effects; D013004:Somatostatin / Q000008:administration & dosage / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D013997:Time Factors; D010566:Virulence Factors, Bordetella / Q000008:administration & dosage / Q000494:pharmacology*
D010566:Virulence Factors, Bordetella; D010656:Phenylephrine; D013004:Somatostatin; D037342:Pertussis Toxin; D005033:Ethylmaleimide