REGIONAL CEREBRAL BLOOD-FLOW DURING SUBMERGENCE ASPHYXIA IN PEKIN DUCK

The cerebrovascular response to submergence asphyxia was studied in th e Pekin duck (Anas platyrhynchos var.) by use of the cerebral blood fl ow (CBF) tracer [C-14]isopropyliodoamphetamine and quantitative autora diography. Blood flow of the whole brain was 158 +/- 14 (SE) ml.min(-1 ).100 g(-1) (n = 7) in control animals. There was a doubling of flow t o 320 +/- 61 ml.min(-1).100 g(-1) (n = 6) during submergence asphyxia. The hypothesis that CBF is redistributed within the brain during asph yxia was not supported. There were no regional reductions in CBF durin g submergence asphyxia. Mean arterial blood pressure was similar (simi lar to 140 mmHg), but heart rate, arterial blood gas tensions, and art erial pH were significantly different in control and submerged ducks a t the time CBF was measured. The differences in CBF among submerged an imals correlated strongly with arterial PCO2, and mean arterial blood pressure. The smallest proportional difference in regional CBF between control and submerged ducks occurred in the ectostriatum (+141%) and the largest in the locus ceruleus (+241%). The largest absolute differ ence in regional CBF was in the nucleus ruber (+ 322 ml.min(-1).100 g( -1)). These are the first measurements of blood flow in discrete nucle i and regions of the avian brain.