Preoptic hypothalamic lesions reduce adrenergic vascular compensation during hemorrhagic shock.
The effect of electrolytic ablation of the periventricular tissue surrounding the anteroventral third ventricle (AV3V-X) of the rat brain on vascular compensation during prolonged hypotensive hemorrhage was determined. Anesthetized AV3V-X and control-operated (Cont) animals were subjected to a modified Wigger's hemorrhagic shock protocol. Maximum bled volume (MBV) was significantly lower in AV3V-X rats (2.74 +/- 0.14 ml/100 g BW) compared with control animals (3.51 +/- 0.16 ml/100 g BW). Pretreatment with the nonspecific alpha-adrenergic antagonist phentolamine (2.74 +/- 0.16 ml/100 g BW) or with the alpha 1-adrenergic antagonist prazosin (2.85 +/- 0.17 ml/100 g BW) reduced MBV in Cont rats, but did not attenuate MBV in AV3V-X animals (phentolamine: 2.33 +/- 0.17 ml/100 g BW; prazosin: 2.4 +/- 0.2 ml/100 g BW). In addition, maximum vasoconstriction was maintained for a significantly shorter period of time in AV3V-X (11.8 +/- 2.5 min) compared with Cont (30.8 +/- 10.5 min). These findings suggest that AV3V-X results in a deficit of alpha 1-adrenoreceptor activation during prolonged hypotension.
Schaumloffel
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Department of Physiology and Biophysics, University of Tennessee, Memphis 38163.
Pugh
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Bealer
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D000818:Animals; D006439:Hemodynamics / Q000187:drug effects; D008297:Male; D010646:Phentolamine / Q000494:pharmacology; D011224:Prazosin / Q000494:pharmacology; D011301:Preoptic Area / Q000503:physiopathology*; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D012771:Shock, Hemorrhagic / Q000503:physiopathology*; D015016:Yohimbine / Q000494:pharmacology
D011942:Receptors, Adrenergic, alpha; D015016:Yohimbine; D011224:Prazosin; D010646:Phentolamine