title: Influence of cyclic nucleotides on junctional permeability in atrial muscle.
abstract: The influence of dB-cAMP (5 X 10(-4) M) and 8-Br-cGMP (5 X 10(-5) M; 5 X 10(-9) M) on the longitudinal diffusion of Lucifer Yellow CH along dog trabeculae was investigated. It was found that dB-cAMP enhances the diffusion coefficient of the dye from 4 +/- 0.63 X 10(-7) cm2/s (control) to 2 +/- 0.53 X 10(-6) cm2/s. Efflux studies showed that the permeability of the surface cell membrane to Lucifer Yellow is negligible ruling out the possibility that the dye moved from cell-to-cell through the extracellular space. The permeability of the nexal membrane (Pnexus = 3 X 4 cm/s) was appreciably enhanced in fibers exposed to dB-cAMP (9.1 X 10(-4) cm/s). No change in the longitudinal redistribution of Lucifer Yellow CH was found with 8-Br-cGMP. The results support the hypothesis that cAMP is a modulator of junctional permeability in the normal heart.
mesh_terms: D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D002463:Cell Membrane Permeability / Q000187:drug effects*; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000494:pharmacology; D004058:Diffusion; D004285:Dogs; D007365:Intercellular Junctions / Q000187:drug effects / Q000378:metabolism*; D007546:Isoquinolines / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*
chemical_list: D007546:Isoquinolines; C016276:8-bromocyclic GMP; D003994:Bucladesine; C017475:lucifer yellow; D006152:Cyclic GMP