AJP - Regulatory, Integrative and Comparative Physiology, Vol 266, Issue 6 1810-R1815, Copyright © 1994 by American Physiological Society
ATP-MgCl2 treatment after trauma-hemorrhage/resuscitation increases hepatocyte P2-purinoceptor binding capacity
M. S. Mahmoud, P. Wang, S. R. Hootman, S. S. Reich and I. H. Chaudry
Department of Surgery, Michigan State University, East Lansing 48824.
Although our studies indicate that P2-purinoceptor binding capacity
decreases after hemorrhage and resuscitation, it is not known whether
ATP-MgCl2 administration after hemorrhage has any beneficial effects on the
receptor dynamics. To study this, we performed laparotomy (i.e., trauma
induced) on rats and bled them to and maintained them at a mean arterial
pressure of 40 mmHg until 40% of maximum bleedout volume was returned in
the form of Ringer lactate (RL). The animals were then resuscitated with 3
times the volume of maximum bleedout with RL over 45 min followed by 2
times RL along with ATP-MgCl2 (50 mumol/kg body wt) over 95 min.
Hepatocytes were isolated at 4, 17, and 27 h after resuscitation.
P2-purinoceptor binding characteristics were determined by using
[alpha-35S]ATP. Scatchard analysis revealed high-affinity and low-affinity
receptor components in the hepatocytes isolated from sham-operated or
hemorrhaged animals with or without ATP-MgCl2 infusion. ATP-MgCl2
ameliorated and subsequently restored the decreased maximum binding
capacity (Bmax) of the high-affinity receptor component and significantly
improved Bmax of the low-affinity receptor component. ATP-MgCl2
administration also produced a progressive enhancement in the affinity of
the low-affinity receptor component. Thus the beneficial effects of
ATP-MgCl2 observed after trauma-hemorrhage and resuscitation may be, in
part, due to the restoration of P2-purinoceptor binding capacity and the
enhancement of the receptor affinity.
