Effects of calcium antagonists, felodipine and nicardipine, on cerebral circulation in dogs.
The effects of a calcium antagonist of the dihydropyridine type, felodipine, on the cerebral circulation were studied in comparison with those of nicardipine in pancuronium-bromide immobilized unanesthetized dogs. Felodipine (0.3-10 micrograms/kg, i.v.) and nicardipine (0.3-10 micrograms/kg, i.v.) produced a dose-related decrease in mean blood pressure with almost equal potencies. However, at a dose of 3 micrograms/kg, felodipine produced a more prominent increase in cerebral blood flow (CBF) than nicardipine. Decreases in cerebral vascular resistance were significantly greater in the felodipine group at doses of 0.3 and 3 micrograms/kg, when compared with the nicardipine group. Cerebral oxygen consumption calculated by multiplying the arterio-venous difference of oxygen content by CBF was increased by these two drugs, but the changes were minimal. These data suggest that the increase in CBF produced by felodipine and nicardipine was primarily due to the direct dilatation of the cerebral blood vessels.
Tanaka
M
M
Department of Pharmacology, Niigata University School of Medicine, Japan.
Yoshida
Y
Y
Mitomi
A
A
Nakazawa
M
M
Imai
S
S
D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D015736:Felodipine / Q000494:pharmacology*; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D009529:Nicardipine / Q000494:pharmacology*; D010101:Oxygen Consumption / Q000187:drug effects
D002121:Calcium Channel Blockers; D009529:Nicardipine; D015736:Felodipine