Paper Report for: Kostka_1989_J.Pharmacol.Exp.Ther_251_305
Reference
Title: Identification and characterization of presynaptic and postsynaptic beta adrenoreceptors in the longitudinal smooth muscle/myenteric plexus of dog ileum Kostka P, Sipos SN, Kwan CY, Niles LP, Daniel EE Ref: Journal of Pharmacology & Experimental Therapeutics, 251:305, 1989 : PubMed
The subcellular distribution of [125I]cyanopindolol (125I-CYP) binding in membrane fractions derived from the longitudinal smooth muscle/myenteric plexus (LSM/MP) of dog ileum followed a bimodal pattern with selective enrichments in the purified synaptosomal (S2) fraction and the purified smooth muscle plasma membrane (M2) fraction. The half-maximal saturation of binding sites in both fractions occurred at 10 pM [125I]CYP with maximal binding capacities, in femtomoles per milligram of protein, 70 +/- 10 (S2 fraction) and 110 +/- 25 (M2 fraction). Approximately 80% of binding sites in either membrane fraction exhibited a high affinity for beta-2 selective antagonist ICI 118,551 (Ki = 1.4 +/- 0.4 nM in S2 and 1.8 +/- 0.6 nM in M2; mean +/- S.D. n = 3), whereas remaining 20% of binding sites had a low affinity for this agent (Ki = 2.6 +/- 1.5 microM in S2 and 0.55 +/- 0.2 microM in M2). The beta-1-selective antagonist ICI 89,406 had a high affinity for approximately 20% of binding sites (Ki = 12 +/- 7 nM in S2 and 4 +/- 2 nM in M2) and a low affinity for approximately 80% of binding sites (Ki = 0.34 +/- 0.16 microM in S2 and 0.42 +/- 0.24 microM in M2). The displacement potencies of beta-adrenergic agonists followed the order (-)-isoproterenol greater than salbutamol (-)-epinephrine greater than (-)-norepinephrine in each membrane preparation. The inclusion of 0.1 mM 5'-guanylylimidodiphosphate into assay medium resulted in a decreased affinity of receptors for agonists and increased values of Hill coefficients.(ABSTRACT TRUNCATED AT 250 WORDS)
        
Related information
Citations formats
Kostka P, Sipos SN, Kwan CY, Niles LP, Daniel EE (1989) Identification and characterization of presynaptic and postsynaptic beta adrenoreceptors in the longitudinal smooth muscle/myenteric plexus of dog ileum Journal of Pharmacology & Experimental Therapeutics251: 305-10
Kostka P, Sipos SN, Kwan CY, Niles LP, Daniel EE (1989) Journal of Pharmacology & Experimental Therapeutics251: 305-10