Beta-receptor-mediated increase in cerebral blood flow during hypoglycemia.
We tested the hypothesis that beta-adrenergic receptor stimulation is involved with the increase in regional cerebral blood flow (rCBF) during hypoglycemia. Rats were surgically prepared with the use of halothane-nitrous oxide anesthesia. A plaster restraining cast was placed around the hindquarters, and anesthesia was discontinued. Hypoglycemia was produced by an intravenous injection of insulin (15 U/kg); normoglycemic control rats were given saline. Propranolol (1.5 mg/kg) was administered to some control and some hypoglycemic rats to block the beta-adrenergic receptors. Regional CBF was measured using 4-[N-methyl-14C]iodoantipyrine. Plasma glucose in the normoglycemic and hypoglycemic groups was approximately 6 and 1.4 mumol/ml, respectively. Regional CBF increased during hypoglycemia in rats that were not treated with propranolol. The increase varied from approximately 60 to 200% depending on the brain region. During hypoglycemia, propranolol abolished the increase in rCBF in the hypothalamus, cerebellum, and pyramidal tract. In other regions the increase in rCBF was only 33-65% of the increase in hypoglycemic rats that were not treated with propranolol. We conclude that beta-receptor stimulation plays a major role in the increase in rCBF during hypoglycemia.
Hollinger
B R
BR
Department of Surgery, Milton S. Hershey Medical Center, Pennsylvania State University, Hershey 17033.
Bryan
R M
RM
D000818:Animals; D000983:Antipyrine / Q000378:metabolism; D001786:Blood Glucose / Q000032:analysis; D002531:Cerebellum / Q000098:blood supply; D002560:Cerebrovascular Circulation; D007003:Hypoglycemia / Q000503:physiopathology*; D007031:Hypothalamus / Q000098:blood supply; D007328:Insulin / Q000494:pharmacology; D008297:Male; D011433:Propranolol / Q000494:pharmacology; D011712:Pyramidal Tracts / Q000098:blood supply; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000502:physiology*
D001786:Blood Glucose; D007328:Insulin; D011943:Receptors, Adrenergic, beta; D011433:Propranolol; D000983:Antipyrine