AIM To investigate the signaling pathways involved in the relaxin(RLX) effects on ileal preparations from mice through mechanical and electrophysiological experiments.METHODS For mechanical experiments, ileal preparat...AIM To investigate the signaling pathways involved in the relaxin(RLX) effects on ileal preparations from mice through mechanical and electrophysiological experiments.METHODS For mechanical experiments, ileal preparations from female mice were mounted in organ baths containing Krebs-Henseleit solution. The mechanical activity was recorded via force-displacement transducers, which were coupled to a polygraph for continuous recording of isometric tension. Electrophysiological measurements were performed in current-and voltage-clamp conditions by a microelectrode inserted in a single smooth muscle cell(SMC) of the ileal longitudinal layer. Both the membrane passive properties and inward voltage-dependent L-type Ca2+ currents were recorded using suitable solutions and voltage stimulation protocols.RESULTS Mechanical experiments showed that RLX induced a decay of the basal tension and a reduction in amplitude of the spontaneous contractions. The effects of RLX were partially reduced by 1 H-[1,2,4]oxadiazolo[4,3-a ]-quinoxalin-1-one(ODQ) or 9-cyclopentyladenine mesylate(9 CPA), inhibitors of guanylate cyclase(GC) and adenylate cyclase(AC), respectively, and were abolished in the concomitant presence of both drugs. Electrophysiological experiments demonstrated that RLX directly influenced the biophysical properties of ileal SMCs, decreasing the membrane conductance, hyperpolarizing the resting membrane potential, reducing the L-type calcium current amplitude and affecting its kinetics. The voltage dependence of the current activation and inactivation time constant was significantly speeded by RLX. Each electrophysiological effect of RLX was reduced by ODQ or 9 CPA, and abolished in the concomitant presence of both drugs as observed in mechanical experiments. CONCLUSION Our new findings demonstrate that RLX influences ileal muscle through a dual mechanism involving both GC and AC.展开更多
基金Supported by University of Florence(ex60%) ROBERTA SQUECCORICATEN15(to Squecco R)
文摘AIM To investigate the signaling pathways involved in the relaxin(RLX) effects on ileal preparations from mice through mechanical and electrophysiological experiments.METHODS For mechanical experiments, ileal preparations from female mice were mounted in organ baths containing Krebs-Henseleit solution. The mechanical activity was recorded via force-displacement transducers, which were coupled to a polygraph for continuous recording of isometric tension. Electrophysiological measurements were performed in current-and voltage-clamp conditions by a microelectrode inserted in a single smooth muscle cell(SMC) of the ileal longitudinal layer. Both the membrane passive properties and inward voltage-dependent L-type Ca2+ currents were recorded using suitable solutions and voltage stimulation protocols.RESULTS Mechanical experiments showed that RLX induced a decay of the basal tension and a reduction in amplitude of the spontaneous contractions. The effects of RLX were partially reduced by 1 H-[1,2,4]oxadiazolo[4,3-a ]-quinoxalin-1-one(ODQ) or 9-cyclopentyladenine mesylate(9 CPA), inhibitors of guanylate cyclase(GC) and adenylate cyclase(AC), respectively, and were abolished in the concomitant presence of both drugs. Electrophysiological experiments demonstrated that RLX directly influenced the biophysical properties of ileal SMCs, decreasing the membrane conductance, hyperpolarizing the resting membrane potential, reducing the L-type calcium current amplitude and affecting its kinetics. The voltage dependence of the current activation and inactivation time constant was significantly speeded by RLX. Each electrophysiological effect of RLX was reduced by ODQ or 9 CPA, and abolished in the concomitant presence of both drugs as observed in mechanical experiments. CONCLUSION Our new findings demonstrate that RLX influences ileal muscle through a dual mechanism involving both GC and AC.
