Release by hypoxia of a soluble vasoconstrictor from rabbit small pulmonary arteries.
Talbot NP., Robbins PA., Dorrington KL.
BACKGROUND: Soluble pulmonary vasoconstrictors released in response to hypoxia have been reported in pig and rat preparations, but not in rabbit preparations. METHODS: We used myography to evaluate the contribution of a soluble factor to constriction in rabbit small pulmonary arteries (external diameter 300-475 microm) exposed to 45 min hypoxia (PO(2)=9 mm Hg). RESULTS: Hypoxia produced gradually intensifying constriction. Return to euoxia (PO(2)=145 mm Hg) for 30 min relaxed only approximately 30% of the constriction, whereas elution of the myograph bath yielded full relaxation. Reapplication of the eluent gradually restored the constriction to its pre-elution level over a 30-min period. CONCLUSIONS: In this closed system, a soluble factor contributes substantially to hypoxic pulmonary vasoconstriction.