AJP - Heart and Circulatory Physiology, Vol 239, Issue 5 636-H641, Copyright © 1980 by American Physiological Society
Brain adenosine production in rat during sustained alteration in systemic blood pressure
H. R. Winn, J. E. Welsh, R. Rubio and R. M. Berne
Brain production of adenosine and its metabolites, inosine and hypoxanthine
was determined in 46 rats during sustained (5 min) reduction in mean
arterial blood pressure (MABP) caused by hemorrhage. Also measured were
ATP, ADP, AMP, phosphocreatine (PCr), and lactate. Brain tissue was
obtained by the freeze-blowing technique. Ventilation was controlled to
maintain constant arterial O2 tension, CO2 tension, and pH. When MABP was
decreased from 135 + 3 (SE) mmHg to 72 +/- 2 mmHg, within the range of
cerebral autoregulation, brain adenosine concentration doubled from 0.55
+/- 0.12 to 1.16 +/- 0.13 nmol/g (P < 0.015). Unlike the changes in
adenosine concentrations, adenine nucleotides and PCr remained stable.
Lactate varied inversely with MABP. With moderate to severe hypotension
(MABP = 45 +/- 3 mmHg), adenosine levels increased almost sixfold. The
increment in brain adenosine concentration within the autoregulatory range
supports a role for this potent dilator of pial vessels in the regulation
of cerebral blood flow.
