The effect of hypoxia on beta-adrenoreceptors in lymphocytes of highlanders

Resumen

 In order to assess the possible role of β-AR desensitization in the genesis of high-altitude pulmonary hypertension (HPAH), we conducted investigations of healthy highlanders in the Kyrgyz National Center of cardiology and internal medicine in Bishkek (760 m above sea level). It was shown that these conditionally healthy highlanders represented the heterogeneous group consisting of 3 subpopulations: 1) nonresponders; 2) hyperresponders; 3) with moderate HPAH. In these three groups the discrepancies of the β-AR response to hypoxia were determined. In nonresponders hypoxia did not change the amount of β-AR (B_max). In hyperresponders under normoxia BMax was decreased compared to normoresponders and hypoxia increased it up to the level of nonresponders. In highlanders with moderate HPAH BMax was initially high and it further increased under hypoxic conditions. Our studies of adenylate cyclase activation under hypoxic conditions demonstrated that basal and agoniststimulated cAMP level in blood lymphocytes were reduced in all three groups of highlanders, that revealed the uncoupling of β-AR with Gs- protein and the development of receptor desensitization.