Effect of captopril on plasma levels of neuropeptide Y (NPY)-like immunoreactivity in the pithed guinea pig.
The effect of exogenous angiotensin II (A II) and the angiotensin converting enzyme (ACE)-inhibitor captopril on plasma levels of neuropeptide Y-like immunoreactivity (NPY-LI) has been studied in the pithed guinea pig. Four periods of pre-ganglionic nerve stimulation (PNS, 8 Hz for 30s with 20 min intervals) were applied and the increases of mean arterial blood pressure (delta BP), heart rate (delta HR) and plasma NPY-LI (delta NPY-LI) in response to PNS were analysed in non-pre-treated and captopril pre-treated animals. Captopril (5 mg x kg-1 i.v.) reduced basal blood pressure and delta BP by 20% and 11%, respectively. Infusion of A II (0.5 microgram x kg-1 = min-1 i.v.) caused a significant increase in basal and PNS-induced maximal blood pressure response but reduced delta BP in captopril and non-pre-treated animals by 40% and 16%, respectively. A II elicited a long-lasting increase of basal heart rate by 12% but reduced delta HR by 36% in non-pre-treated animals. However, neither captopril alone nor A II infusion to captopril pre-treated animals significantly changed heart-rate values. The effects of exogenous A II on the cardiovascular responses were abolished by the A II-antagonist saralasin (a bolus injection, 40 micrograms x kg-1 i.v. followed by an infusion, 30 micrograms x kg-1 x min-1), which per se had no significant effect. Captopril pre-treatment reduced basal plasma NPY-LI levels by 38% and delta NPY-LI by 46% in response to PNS 1. However, neither in non-pre-treated nor in captopril pre-treated animals did infusion of A II significantly change the plasma NPY-LI level.(ABSTRACT TRUNCATED AT 250 WORDS)
Dahlöf
P
P
Department of Clinical Pharmacology, Sahlgrenska Hospital, Gothenburg University, Sweden.
Lundberg
J M
JM
Dahlöf
C
C
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002216:Captopril / Q000494:pharmacology*; D004558:Electric Stimulation; D005728:Ganglia, Sympathetic / Q000187:drug effects; D006168:Guinea Pigs; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D009474:Neurons / Q000187:drug effects; D009478:Neuropeptide Y / Q000097:blood* / Q000276:immunology; D011863:Radioimmunoassay; D012504:Saralasin / Q000494:pharmacology; D009435:Synaptic Transmission / Q000187:drug effects
D009478:Neuropeptide Y; D000804:Angiotensin II; D002216:Captopril; D012504:Saralasin