title: Forskolin, but not alcohol, counteracts desensitization of cyclic AMP accumulation to beta-adrenergic stimulation in rat parotid.
abstract: Forskolin at concentrations of 10 microM and above stimulates cyclic AMP accumulation in rat parotid slices. At concentrations as low as 0.1 microM forskolin also markedly potentiates the effect of isoproterenol in cyclic AMP accumulation, doing so with only slight effect on isoproterenol potency. Organic solvents such as 1-propanol are also known to potentiate the effect of isoproterenol on cyclic AMP accumulation in this tissue, although by itself propanol has little effect (2,3). The unpotentiated effect of isoproterenol is to produce only transient stimulation of cyclic AMP accumulation: Within 30 min after addition of isoproterenol cyclic AMP accumulation is nearly completely desensitized to further effects of the agonist (2). Such desensitization already established to isoproterenol (1 microM) is counteracted by 1 microM or 100 microM forskolin but not by 0.1 microM forskolin or any concentration of 1-propanol. Forskolin (1 microM or greater) potentiates isoproterenol stimulated cyclic AMP accumulation to the same degree, and at the same initial rate, in parotid tissue regardless whether it had been desensitized by pre-exposure to isoproterenol. Although 0.27 M 1-propanol potentiates the acute (2 min) 1 microM isoproterenol response to approximately the same extent as does 1 microM forskolin, no concentration of 1-propanol counteracts desensitization to isoproterenol.
mesh_terms: D000433:1-Propanol / Q000494:pharmacology; D000818:Animals; D005576:Colforsin; D000242:Cyclic AMP / Q000378:metabolism*; D004224:Diterpenes / Q000494:pharmacology*; D004351:Drug Resistance; D004357:Drug Synergism; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D008297:Male; D010306:Parotid Gland / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004224:Diterpenes; D005576:Colforsin; D000433:1-Propanol; D000242:Cyclic AMP; D007545:Isoproterenol