In vivo responses of allografted cerebral parenchymal arterioles to ethanol and angiotensin II: effect of calcium channel blockade.
The goals of these studies were to determine: 1) the effect of ethanol and angiotensin II on the diameter of allografted cerebral parenchymal arterioles in vivo, and 2) the effect of the calcium antagonist, verapamil, in modulating the responses of allografted cerebral parenchymal arterioles to ethanol and angiotensin II. Using a chamber technique, neonatal (< 24 hours old) cortical tissue was transplanted onto the cheek pouch of adult hamsters. Eight to thirteen days after allografting, hamsters were anesthetized with sodium pentobarbital (6.0 mg/100 grams i.p.), and allografted cerebral parenchymal arterioles were viewed using intravital microscopy. Diameter of allografted cerebral parenchymal arterioles was measured before (control), during and after topical application of ethanol (0.1%, 0.25%, 0.5%, 1.0%, and 2.0%) and angiotensin II (0.1 and 1.0 ng/ml). Application of ethanol and angiotensin II was repeated after changing the suffusion fluid to one containing verapamil (50 mg/L). We found that ethanol and angiotensin II produced dose-related constriction of allografted cerebral parenchymal arterioles. In addition, verapamil significantly attenuated vasoconstriction produced by ethanol and angiotensin II. Thus, our findings suggest that ethanol and angiotensin II cause constriction of allografted cerebral parenchymal arterioles through a calcium-dependent mechanism.
Yong
T
T
Department of Physiology and Biophysics, University of Nebraska Medical Center, Omaha.
Gilmore
J P
JP
Joyner
W L
WL
Mayhan
W G
WG
D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000637:transplantation; D001921:Brain / Q000098:blood supply*; D002118:Calcium / Q000502:physiology*; D002610:Cheek; D006224:Cricetinae; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D008647:Mesocricetus; D016042:Transplantation, Heterotopic; D014184:Transplantation, Homologous; D014700:Verapamil / Q000494:pharmacology*
D000804:Angiotensin II; D000431:Ethanol; D014700:Verapamil; D002118:Calcium