The effect of hypoxia on the branchial vascular system of the perfused trout head.

Measurements of inflow (VE) and arterial (Vsa) and venous (VSv) outflow in trout perfused head preparations show significant decreases of VE and VSa during low PO2 saline perfusion (20 torr). Comparable results are gained during adenosine perfusion (1.10(-8) to (1.10(-6) M). Theophylline (10(-4) M) inhibits both hypoxia and adenosine effects.