Effect of dopamine receptor anatagonists on the calcium-dependent central function that reduces blood pressure in spontaneously hypertensive rats.
The effects of intracerebroventricular (i.c.v.) administration of dopamine receptor antagonists on the calcium-dependent brain function that reduces blood pressure were investigated. The systolic blood pressure of spontaneously hypertensive rats (SHR; male, 13 weeks of age) was reduced following i.c.v. administration of calcium chloride (100 microg/rat), and this effect of calcium chloride was attenuated by i.c.v. injection of eticlopride (dopamine D2 receptor antagonist, 100 microg/rat), but not by i.c.v. injection of SCH 23390 (dopamine D1 receptor antagonist, 30 microg/rat). Taking into consideration these results with our previous reports, it is suggested that calcium enhances dopamine synthesis in the brain through a calmodulin-dependent system, and that the resultant increase in dopamine levels inhibits sympathetic activity via the dopamine D2 receptor in the brain and reduces the blood pressure in SHR.
Sutoo
D
D
Institute of Medical Science, University of Tsukuba, Japan. dsutoo@md.tsukuba.ac.jp
Akiyama
K
K
D000818:Animals; D001552:Benzazepines / Q000008:administration & dosage / Q000494:pharmacology*; D002122:Calcium Chloride / Q000008:administration & dosage / Q000494:pharmacology*; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology / Q000503:physiopathology; D018492:Dopamine Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D065127:Dopamine D2 Receptor Antagonists; D006973:Hypertension / Q000188:drug therapy* / Q000235:genetics / Q000503:physiopathology; D007276:Injections, Intraventricular; D008297:Male; D051381:Rats; D011918:Rats, Inbred SHR; D017447:Receptors, Dopamine D1 / Q000037:antagonists & inhibitors; D012457:Salicylamides / Q000008:administration & dosage / Q000494:pharmacology*; D013599:Systole / Q000187:drug effects*
D001552:Benzazepines; D018492:Dopamine Antagonists; D065127:Dopamine D2 Receptor Antagonists; D017447:Receptors, Dopamine D1; D012457:Salicylamides; C045989:eticlopride; D002122:Calcium Chloride