The development of physiologic responsiveness to muscarinic agonists in chick embryo heart cell cultures. Role of high affinity receptors and sensitivity to guanine nucleotides.

摘要: Abstract Prior to ingrowth of the vagus nerve (4-5 days in ovo), embryonic chick hearts are relatively unresponsive muscarinic stimulation ( Pappano , A. J. (1977) Pharmacol. Rev. 29, 3-33). We studied correlation between development physiologic responsiveness heart and changes properties receptors. In cultures from 10 ovo, agonists decreased beating rate by 15% increased K+ efflux 35%. 3 1/2 receptors had no effect on mediated only an 11% increase efflux. previously demonstrated that cells cultured 26% bound agonist with a high affinity (RH) incubation guanine nucleotides conversion RH low form (RL Galper B., Dziekan L. C., O' Hara D. S., Smith, T. W. (1982) Biol. Chem. 237, 10344-10356]. constituted 52% total [3H] quinuclidinyl benzilate-binding sites, RL. Growth ovo medium supplemented specific lots serum resulted 3-fold (from 11 30%) ability permeability. This sensitivity was accompanied 20% 75% nucleotides. Thus, enhanced number nucleotide associated response. The relationship these developmental appearance regulatory protein is discussed.