ADAPTATION OF PHARMACOMECHANICAL COUPLING OF VASCULAR SMOOTH-MUSCLE TO CHRONIC HYPOXIA

Hypoxia is one of the most common stresses that affect an organism's h omeostasis. Although much is known of the mechanisms of the cellular a nd biochemical responses to acute hypoxia, relatively little is known of the mechanisms of the responses to prolonged or chronic hypoxia. Ch ronic hypoxia suppresses vascular smooth muscle contractility in many vascular beds. While the endothelium is likely to play a role, part of the mechanisms underlying chronic hypoxic-induced changes in vascular responses resides in the changes in receptor-mediated excitation-cont raction coupling and/or signal transduction in the vascular smooth mus cle. Recent studies have demonstrated that chronic hypoxia attenuates both receptor-second messenger and second messenger-contraction coupli ng efficiencies in the vascular smooch muscle. This suppression of pha rmacomechanical coupling is likely to represent one of the adaptive me chanisms of vascular smooth muscle and to Flay an important role in an adjustment of vascular tone and blood flow under the stress of modera te chronic hypoxia. (C) 1998 Elsevier Science Inc.