alpha- and beta-adrenergic receptors in regulation of ionic transport in frog cornea.
The effect of catecholamines and adrenergic blocking agents on the transport of Cl- and Na+ of the isolated frog cornea was studied. Cl- transport was stimulated by the three catecholamines tested at 10(-6) to 10(-5) M concentration. The stimulation produced by 10(-6) M epinephrine was partially inhibited by both the alpha-blocker phentolamine and the beta blocker propranolol. The stimulation produced by 10(-6) M isoproterenol was not affected by 10(-5) M phentolamine but was completely prevented by 10(-5) M propranolol. The stimulation produced by 10(-5) M norepinephrine was completely blocked by the 10(-5) M propranolol and partially by 10(-5) M phentolamine. Catecholamines had no effect on the normally small Na+ transport. When the Na+ transport was previously increased by amphotericin B, epinephrine and isoproterenol produced a small and inconsistent stimulatory effect. Norepinephrine was without effect. It is concluded that both alpha- and beta-adrenergic receptors are present in the frog cornea and that the Cl- transport is increased by the stimulation of either receptor. The minimal effect on the Na+ transport further suggests the separation of pathways of the Cl- and Na+ transport in the frog cornea.
D000818:Animals; D001693:Biological Transport, Active / Q000187:drug effects; D002712:Chlorides / Q000378:metabolism*; D003315:Cornea / Q000378:metabolism*; D004837:Epinephrine / Q000494:pharmacology; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects; D009638:Norepinephrine / Q000494:pharmacology; D010646:Phentolamine / Q000494:pharmacology; D011433:Propranolol / Q000494:pharmacology; D011892:Rana catesbeiana; D011941:Receptors, Adrenergic; D012964:Sodium / Q000378:metabolism*
D002712:Chlorides; D011941:Receptors, Adrenergic; D012964:Sodium; D011433:Propranolol; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine; D010646:Phentolamine