Effect of prazosin on microvascular perfusion during middle cerebral artery ligation in the rat.
The purpose of this study was to evaluate the effects of prazosin, an alpha 1-adrenoceptor antagonist, on morphometric indexes of the total and perfused cerebral microvascular bed 1 hour after middle cerebral artery (MCA) ligation in pentobarbital-anesthetized rats. We hypothesized that this agent would prevent catecholamine-induced vasoconstriction in the ischemic brain. Cerebral blood flow (CBF) was determined with 14C-iodoantipyrine, and the perfused microvascular bed was visualized using fluorescein isothiocyanate-dextran. MCA occlusion did not alter systemic hemodynamic or blood gas parameters. CBF averaged 29 +/- 15 (mean +/- SD) ml/min/100 g in the MCA-ligated cortex and 49 +/- 18 in the other examined brain regions. Prazosin did not significantly alter these CBF values, averaging 26 +/- 14 and 48 +/- 10, respectively. There were no significant regional differences in total capillaries/mm2 in either group. The percent of the capillaries/mm2 perfused (51 +/- 6%) was similar in the two groups in all examined regions except the ischemic cortex. In the MCA-ligated cortex, 22 +/- 8% of the capillary volume was perfused in comparison with 49 +/- 8% in the prazosin-treated group. Prazosin-treated rats had an increased percentage of their microvasculature perfused despite a similarly reduced CBF. Prazosin appeared to reduce diffusion distances in the ischemic cortex. This might be due to its alpha 1-adrenoceptor blocking activity.
Anwar
M
M
Department of Physiology and Biophysics and Pediatrics, UMDNJ-Robert Wood Johnson Medical School, Piscataway 08854-5635.
Buchweitz-Milton
E
E
Weiss
H R
HR
D000818:Animals; D001794:Blood Pressure; D002536:Cerebral Arteries / Q000502:physiology*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D005260:Female; D006439:Hemodynamics; D008026:Ligation; D008297:Male; D008833:Microcirculation / Q000187:drug effects; D010477:Perfusion; D011224:Prazosin / Q000494:pharmacology*; D051381:Rats
D011224:Prazosin