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α‐Adrenoceptor involvement in catecholamine‐induced hyperglycaemia in conscious fasted rabbits
Author(s) -
Moratinos J.,
Olmedilla B.,
Pablos I.,
Vigueras M.D.
Publication year - 1986
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1986.tb11120.x
Subject(s) - phenylephrine , medicine , phenoxybenzamine , endocrinology , prazosin , glycogenolysis , insulin , yohimbine , catecholamine , epinephrine , glycogen , chemistry , propranolol , blood pressure , antagonist , receptor
1 In conscious fasted rabbits an intravenous infusion of phenylephrine (20 μg kg −1 min −1 ) induced hyperglycaemia. The increase in blood glucose was accompanied by a modest increase in insulin secretion and a reduction of liver glycogen. Muscle glycogen and blood lactate levels were not altered by treatment with phenylephrine. 2 Prazosin, 1 mg kg −1 s.c, partially attenuated phenylephrine‐induced hyperglycaemia. 3 Phenoxybenzamine infusion (16.6 μg kg −1 min −1 ) for 15 min suppressed the increase in blood glucose and the reduction in liver glycogen evoked by phenylephrine. This α‐adrenoceptor blocker also clearly attenuated the blood glucose elevation observed on infusing adrenaline at 0.3 μg kg −1 min −1 . 4 Blockade by phenoxybenzamine of phenylephrine‐ and adrenaline‐induced hyperglycaemia was not accompanied by a significant increase in immunoreactive insulin plasma levels. 5 Yohimbine infused at a rate of 20 μg kg −1 min −1 , also completely blocked phenylephrine‐induced hyperglycaemia. This suppressor effect was accompanied by a marked rebound in insulin secretion. 6 It is concluded that in normal fasted rabbits stimulation of α‐adrenoceptors induces hyperglycaemia. The increase in blood glucose depends mainly on liver glycogenolysis and inhibition of insulin secretion. Separate blockade of each component suffices to reduce α‐adrenoceptor‐mediated hyperglycaemia.