Ca²⁺ Channels and Chronic Hypoxia

Abstract

Many chronic lung diseases are associated with prolonged exposure to alveolar hypoxia, resulting in the development of pulmonary hypertension. While the exact mechanisms underlying the pathogenesis of hypoxic pulmonary hypertension remain poorly understood, a key role for changes in Ca²⁺ homeostasis has emerged. Intracellular Ca²⁺ concentration controls a variety of pulmonary vascular cell functions, including contraction, gene expression, growth, barrier function and synthesis of vasoactive substances. Several studies indicate that prolonged exposure to hypoxia causes alterations in the expression and activity of several Ca²⁺ handling pathways in pulmonary arterial smooth muscle cells. In contrast, the effect of chronic hypoxia on Ca²⁺ homeostasis in pulmonary arterial endothelial cells is relatively unexplored. In this review, we discuss data from our laboratory and others describing the effects of prolonged hypoxia on pulmonary vascular smooth muscle and endothelial cell Ca²⁺ homeostasis and the various Ca²⁺ channels and handling pathways involved in these responses. We will also highlight future directions of investigation that might improve our understanding of the response of pulmonary vascular cells to chronic hypoxia.

KEYWORDS:

• endothelial cells
• hypoxic pulmonary hypertension
• smooth muscle cells

The authors acknowledge the excellent technical assistance from Clark Undem and Trevor Luke in contributing to this work. The work was supported by grants from the NIH (HL67191 and HL51912) and the American Heart Association (AHA0430037N).