Hypoxia-induced regression of adaptive structural microvessel reactions caused by long-term contraction influences in...

Chronic effects of hypobaric hypoxia (hb.h.) on the microcirculatory system (m.s.) of skeletal muscle were investigated. A new histomorphometric method was applied to detect the adaptive structural reactions of wall cells to long term changes in contraction performance. Seventeen SHR were exposed to hb.h. from 5 to 18 or 17 to 30 weeks of life, respectively. For controls 19 SHR and 25 normotensive Wistar rats were kept at sea level. The findings document long-term actions of vasorelaxation factors in hb.h. and the ability of the latter to antagonize the intensified vasocontraction factors in SHR. Depending on the stage of hypertension, there are different preferential sides for the actions of both these factors within the various districts of the m.s.