title: Central interactions between dihydropyridines and cholinergic systems in the control of blood pressure in rat.
abstract: Intracerebroventricular (i.c.v.) injection of the 1,4-dihydropyridine (DHP) calcium channel agonist, Bay K8644 (30 micrograms/kg) increased mean blood pressure and the K+-evoked release of [3H]acetylcholine ([3H]ACh) from hippocampal slices in spontaneously hypertensive rats (SHR). The Bay K8644-induced hypertension was inhibited by a pretreatment with methylatropine (80 micrograms/kg i.c.v.). In SHR, nicardipine, a DHP calcium channel antagonist, reduced mean blood pressure when i.c.v. injected (10 micrograms/kg). The nicardipine-induced hypotension was reduced by a pretreatment with hemicholinium-3 (20 micrograms, i.c.v.). Nicardipine (1 microM) did not modify, in SHR, the K+-evoked release of [3H]ACh, but inhibited the Bay K8644-induced increase in the ACh release. In normotensive rats, neither Bay K8644 nor nicardipine modify blood pressure, when centrally injected, or the stimulated release of [3H]ACh from hippocampal slices. The participation of central DHP sites in the cholinergic transmission in genetic hypertension is discussed.
mesh_terms: D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology*; D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001286:Atropine Derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D004095:Dihydropyridines / Q000494:pharmacology*; D006426:Hemicholinium 3 / Q000494:pharmacology; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects / Q000502:physiology*; D066298:In Vitro Techniques; D008297:Male; D009529:Nicardipine / Q000494:pharmacology*; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011919:Rats, Inbred Strains; D012016:Reference Values; D013045:Species Specificity
chemical_list: D001286:Atropine Derivatives; D004095:Dihydropyridines; D006584:Hexamethonium Compounds; D006426:Hemicholinium 3; D018738:Hexamethonium; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; C038806:1,4-dihydropyridine; C006649:methylatropine; D009529:Nicardipine; D000109:Acetylcholine; D011188:Potassium