Propranolol Treatment Inhibits the Carotid Body Vascular Changes Evoked by Long-Term Hypoxia

Abstract

Exposure to chronic hypoxia, induced by high altitude or in a normobaric chamber, elicits a number of structural and biochemical changes in the carotid body. One of the most obvious alterations, observed in man as well as in other species, is a general enlargement of the organ. Recently we showed, in intact and sympathectomized rat carotid bodies, that this enlargement is partly due to an increased vascularity (Pequignot and Hellstrom, 1983). The change in vascularity is initially caused by vasodilatation followed by an ingrowth of newly formed blood vessels. Concomitant with the increased vasularity both dopamine (DA). and norepinephrine (NE) levels increased dramatically (Hanbauer et al. 1981). The mechanisms causing these structural and biochemical changes are however unknown. Nor is it known whether these changes are interelated e.g.: is an increased vascularity a prerequisite for Type 1 cell hypertrophy?