[Effects of alpha- and beta-adrenergic blockers on the lower limits of cerebral blood flow autoregulation in spontaneously hypertensive rats].
The effects of alpha- and beta-adrenergic blockers (phenoxybenzamine, PBZ and propranolol, PPL, respectively) on the cerebral (CBF) and cerebellar (CeBF) blood flow autoregulations were examined in spontaneously hypertensive rats. CBF and CeBF were measured during stepwise hemorrhagic hypotension using hydrogen clearance method. The lower limits of autoregulation for CBF beyond which blood flow was decreased steeply were 72% of the resting blood pressure level in the control, 56% in the PBZ treated group, and 80% in the PPL group. Similar tendency was observed in CeBF. These results indicate that PBZ leads to a downward shift while PPL to a slight upward shift of the lower limits of CBF and CeBF autoregulations, suggesting that alpha-adrenergic blockade has a favorable effect for the maintenance of cerebral blood flow during acute reduction of blood pressure.
Sadoshima
S
S
Second Department of Internal Medicine, Faculty of Medicine, Kyushu University, Fukuoka.
Okada
Y
Y
Ooboshi
H
H
Shiokawa
O
O
Fujishima
M
M
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000319:Adrenergic beta-Antagonists / Q000494:pharmacology*; D000818:Animals; D002560:Cerebrovascular Circulation / Q000187:drug effects*; D005260:Female; D006487:Hemostasis / Q000187:drug effects*; D006973:Hypertension / Q000503:physiopathology*; D051381:Rats; D011918:Rats, Inbred SHR
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists