[Combined effect of intracerebroventricular injections of angiotensin II, met-enkephalin and acetylcholine on mean arterial pressure in albino rats].
Single and combined effects of intracerebroventricular bolus injection of Ang. II (200 ng), ACh (6 micrograms) and met-enkephalin (50 micrograms) on mean arterial pressure (MAP), was tested in Sprague-Dawley albino rats. A metallic cannula was implanted in the third ventricle according to standard stereotaxic procedures under pentobarbital anesthesia (35 mg/kg). On the third day, the animal was anesthetized again, a carotid artery was cannulated and connected to a pressure transducer for recording of MAP. Ang. II increased MAP; ACh produced a significant increase in the initial 5 minutes after injection and met-enkephalin did not induce any significant changes in MAP. The combined effect showed interesting results. Instead of a potentiation of the rise in MAP, Ang. II and ACh, when given together, did not show any significant changes. Also, met-enkephalin blocked the hypertensive response due to Ang. II, if given combined. This is compatible with an inhibitory action of met-enkephalin on an angiotensinergic neuronal system. A simplified hypothetical model that explains the findings described above is proposed as a working hypothesis.
Ulate Montero
G
G
Departamento de Farmacología, Escuela de Medicina, Universidad de Costa Rica.
Morales Matamoros
O
O
D000109:Acetylcholine / Q000008:administration & dosage / Q000494:pharmacology*; D000804:Angiotensin II / Q000008:administration & dosage / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D004338:Drug Combinations; D004744:Enkephalin, Methionine / Q000008:administration & dosage / Q000494:pharmacology*; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D011919:Rats, Inbred Strains
D004338:Drug Combinations; D000804:Angiotensin II; D004744:Enkephalin, Methionine; D000109:Acetylcholine
Efecto combinado de angiotensina II, met-encefalina y acetilcolina administradas intracerebroventricularmente sobre la presión arterial media en ratas albinas.