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The electromechanical coupling in the smooth muscles of cat stomach was studied in Ca2+-free solutions containing EGTA. The experiments were carried out on circular muscle strips from the corpus of cat stomach using the single sucrose gap technique. Complete disappearance of the spontaneous electrical and contractile activity of the muscle strips was(More)
In contraction studies corticotropin-releasing hormone (CRH) was found to relax ileal but not gastric and jejunal smooth muscles of the guinea-pig, precontracted with BaCl2. Under whole-cell patch-clamp conditions, CRH concentration-dependently activated Ca2+-sensitive K+ currents (IK) with ED50=20 pM at 100 nM and ED50=0. 13 pM at 500 nM intracellular Ca2+(More)
The effects of cyclopiazonic acid and its combination with ryanodine on the inward Ca2+ current (ICa) were investigated in smooth muscle cells isolated from the circular layer of guinea-pig ileum. The ICa of these cells exhibited two components: a low-threshold, nicardipine (5 microM)-resistant, fast-inactivating component and a high-threshold,(More)
In some smooth muscle cells, the rise in intracellular Ca2+ as a result of a Ca2+ influx via plasma membrane Ca2+ channels can activate a further increase in intracellular Ca2+ as a result of Ca2+ release from intracellular stores. This study examined the role of the Ca2+-induced Ca2+ release from the ryanodine-sensitive intracellular Ca2+ stores in shaping(More)
The ionic currents in the membrane of the body of single T- and N-mechanosensory neurons were studied. Transient inward NA+-current followed by outward K+-current was recorded in the T-cells. The current was activated at membrane potential of -40 mV, reaching its maximum at -10 mV for 2 ms, whereby the reversal potential was about 25 mV. This current was(More)
In the majority of experiments the ruminal preparations did not exhibit spontaneous electrical and contractile activity but showed a Ca-dependent spike-free myogenic tone. Ba2+ or Sr2+ evoked spike activity and phasic contractions and increased the muscle tonic tension. Tetraethylammonium (TEA) exerted no effect on the ruminal preparations but potentiated(More)
K+ outward currents (I[K]) expressed by guinea-pig antral smooth muscle cells were studied using the whole-cell voltage-clamp technique. In about 88% of cells depolarization steps applied from Vh = -70 mV activated a fast transient component (I[K(to)]) with voltage-dependent characteristics, and a noninactivating component with slow activation kinetics(More)
The aim of the present study is to characterize voltage-sensitive macroscopic K+ current (IK) components in freshly isolated human colonic smooth muscle cells. IK components were studied by the conventional whole-cell voltage clamp method. We found two main components of IK. A transient IK component with fast kinetics, IK(fi), activated upon a holding(More)
Three different populations of voltage-activated K+ channels were identified according to their voltage-dependences, inactivation kinetics and sensitivity toward selective K+ channels antagonists in membranes of cells, isolated from the circular layer of guinea-pig ileum by the use of whole-cell voltage clamp method. Under holding potential Vh = -50 mV(More)
The relationship between inositol-1,4,5-trisphosphate-sensitive Ca2+ stores and Ca2+ entry through potential-dependent L-type Ca2+ channels was examined using whole-cell voltage-clamp technique in cells of longitudinal muscle layer of guinea-pig ileum. It was found that heparin (10(-10) mol/l) in the pipette rapidly inhibited the current through L-type Ca2+(More)