Effects of Verapamil and BAY K 8644 on the Hypoxic Contraction of the Isolated Human Pulmonary Artery

Abstract

To examine the effect of hypoxia on the human pulmonary artery (HP A), HP A segments (2 mm, o.d.) were suspended and changes in isometric force with hypoxia (Po2 = 44±3 mmHg, mean±s.E.) were measured. HP A contracted with hypoxia and the tension developed with 15 min of hypoxia was 127 ± 36 (mean±s.E.) mg. Verapamil at 10-6 M inhibited and 10-6 M BAY K 8644 enhanced the hypoxic response by 47±10% (p<0.01) and 396±106% (p<0.05), respectively, compared with preceding values. These results show that activation of voltage-dependent Ca2+ channels also plays an important role in the mechanism of hypoxic pulmonary vasoconstriction in man. © 1989, Tohoku University Medical Press. All rights reserved.