Effect of insulin on regional vascular resistances in conscious
rats.
Qadir, Ehsan, and James P. Porter.
Department of Physiology and The Center for Applied
Microcirculatory Research, University of Louisville, Louisville, KY
40292, Phone: 502-852-7219, FAX: 502-852-6239
APStracts 2:0272R, 1995.
In the rat, but not in humans and other mammals, chronic
administration of insulin produces hypertension. The present aim was
to determine the effect of acute insulin infusion on regional
vascular resistances and to determine the neurogenic contribution to
the response. Conscious rats were infused with insulin (2 or 6
mU/min) before and after ganglionic blockade with chlorisondamine (5
mg/kg). The low dose of insulin produced an increase in arterial
pressure and hindquarter vascular resistance, the high dose produced
a gradual decrease in arterial pressure and renal resistance.
Following ganglionic blockade, the hindquarter vasoconstriction
produced by the low dose was abolished. The high dose of insulin
produced both hindquarter and renal vasodilation. Thus, the low dose
of insulin had a selective neurogenic vasoconstrictor effect in rat
skeletal muscle vascular beds. With higher doses, direct vasodilatory
effects in both skeletal muscle and renal vascular beds appeared.
This greater sensitivity of the sympathoexcitatory effects of insulin
in rats may explain the ability of chronic insulin infusions to
increase blood pressure in this species.
Received 27 December 1994; accepted in final form 24 August 1995.
APS Manuscript Number R736-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 14 November 95