Abstract
Whereas much information has accumulated on myocardial adrenergic mechanisms in adult man, little is known about these mechanisms in the newborn child. The effects of norepinephrine (NE), isoproterenol (ISO), cocaine (C, 3×10−6M) and propranolol (P, 1×lO−6M) on contractile function were examined in isometrically contracting right atrial strips of 7 children age 5 months to 9 years, as well as in 4 papillary muscles and 3 atrial strips obtained at autopsy from 6 premature (estimated gestational age 18–34 weeks) and 1 full term infant. Dose-response curves to ISO in both groups were linear, parallel, and statistically identical. NE dose-response curves in both groups were also identical and shifted to the right of the ISO curves. P shifted the NE dose-response curve to the right in both groups to the same degree. Whereas C shifted the NE dose-response curve to the left in children, no shift was found in the newborn indicating that sympathetic innervation of the myocardium appears to be incomplete or functionally immature at birth in man. β-adrenergic receptors on the other hand are equally developed in the markedly premature infant and the older child and the myocardium may be expected to respond to catecholamines and β-adrenergic blockade in a similar manner in the two groups.
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Faulkner, S., Boerth, R. & Graham, T. POSTNATAL DEVELOPMENT OF SYMPATHETIC INNERVATION OF HUMAN MYOCARDIUM. Pediatr Res 8, 362 (1974). https://doi.org/10.1203/00006450-197404000-00135
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DOI: https://doi.org/10.1203/00006450-197404000-00135