Ontogeny of alpha 1-adrenergic receptors in the rat myocardium: effects of hypothyroidism.
The effects of propylthiouracil (PTU) treatment on alpha 1- and beta-adrenergic receptors in neonatal and adult rat myocardium were examined with the alpha 1-selective antagonist [3H]prazosin and beta-antagonist (-)-[3H]dihydroalprenolol ((-)-[3H]DHA). Pre and postnatal PTU treatment (congenital hypothyroid state) decreased ventricular size and protein content at 15 and at 28 days (P less than 0.01). Similarly PTU treatment after maturation (acquired hypothyroid state) is associated with decreased ventricular size and protein content (P less than 0.01). PTU treatment did not alter ventricular DNA content at any age examined as compared to euthyroid controls. Specific [3H]prazosin binding to ventricular membrane increased with advancing postnatal age in both congenital hypothyroid pups and controls, reaching peak receptor density at 15 days of postnatal age (106 +/- 8 vs. 151 +/- 7 fmol X mg-1 protein). The density at 15 and 28 days was however significantly lower in hypothyroid pups (P less than 0.01, P less than 0.02). The effect of congenital hypothyroidism on (-)-[3H]DHA binding was more marked which significantly decreased from the first postnatal day. Acquired hypothyroidism is also associated with a decreased density of alpha 1- and beta-adrenergic receptors in rat myocardium. We conclude that alpha 1- and beta-adrenergic receptors are modulated by thyroid hormone in developmental as well as mature stages of the rat.
D000818:Animals; D000831:Animals, Newborn / Q000254:growth & development / Q000378:metabolism; D003409:Congenital Hypothyroidism; D004082:Dihydroalprenolol; D006321:Heart / Q000254:growth & development*; D007037:Hypothyroidism / Q000503:physiopathology*; D007700:Kinetics; D009206:Myocardium / Q000378:metabolism*; D011224:Prazosin; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000502:physiology*; D011942:Receptors, Adrenergic, alpha / Q000502:physiology*; D011943:Receptors, Adrenergic, beta / Q000378:metabolism
D011941:Receptors, Adrenergic; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D004082:Dihydroalprenolol; D011224:Prazosin