Effect of chronic hypoxia on cardiac beta-adrenergic and muscarinic receptors during maturation.

The effect of hypoxia on cardiac beta-adrenergic and muscarinic receptors during the first 3 weeks of postnatal development was determined in the rabbit. After the first week of postnatal exposure to hypoxia, there was no change in the ventricular content of beta-adrenergic receptors. However, after 2 weeks of hypoxia, there was a 24% decrease in the receptor content of the left ventricle with no change in the right ventricle. At the end of 3 weeks exposure to hypoxia, the receptor content had decreased by 31% and 32% in the right and left ventricle, respectively. In control animals, there was no alteration in the beta-adrenergic receptor content of either ventricle over the 3 week period. In contrast to the beta-adrenergic receptor, there was no hypoxia-associated alteration in the muscarinic receptor content of either ventricle during the 3 weeks of postnatal study. The data suggest that hypoxia during the first 3 weeks of postnatal development in the rabbit induces alterations in the cardiac beta-adrenergic receptor with no effect on the development of the cholinergic muscarinic receptor.