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S Kurihara

Publications and source records attributed to S Kurihara.

At least 253 records · Page 14Linked to original sources
PubMed1975

The effect of procaine on the mechanical and electrical activities of the smooth muscle cells of the guineal pig urinary bladder.

Procaine (1-15 mM) enhanced the spontaneous contractions of the urinary bladder smooth muscle. When a low concentration of procaine was added to normal Krebs solutions, spontaneous rhythmic contractions were enhanced. On increasing the concentration of procaine, a rise in tone (resting tension) of the preparation was observed and gradually decreased with time. The action of procaine of enhancing spontaneous contraction was observed in Na-deficient (sucrose substitutiona) and Na-free (Tris substitution) Krebs solutions. Tetrodotoxin (3 X 10(-7) G/M) DID NOT INHIBIT THE EFFECT OFPROCAINE ON MECHANICAL RESPONSE. In normal Krebs solution, procaine depolarized the membrane and increased spike frequency. The peak potential of the spike increased at 1 mM of procaine, but was suppressed at concentrations of more than 5mM. After-hyperpolization of the spike was diminished by procaine and spike duration was prolonged. The maximum rate of rise of the spike was increased immediately after application of 1 mM of procaine, but decreased wiith time. The maximum rate of fall of the spike was markedly decreased by procaine. Relative membrane resistance was increased by the application of procaine. From these results it is suggested thatprocaine mainly reduces K conductance and causes depolarization, and that enhanced spontaneous contractions are caused by depolarization and increased spike activity.

Animals↗
PubMed1974

Effects of rapid cooling on the electrical properties of the smooth muscle of the guinea-pig urinary bladder.

The effects of low temperature (36-10 degrees C) on the electrical properties of smooth muscle cells of the urinary bladder were investigated with microelectrodes and the double sucrose gap method.1. Lowering the temperature from 36 to 20 and to 10 degrees C, depolarized the membrane from -37 to -33 and to -25 mV respectively. Spontaneous and propagated spike activity ceased completely at below 20 degrees C but evoked spikes were occasionally observed at 10 degrees C. A sustained contracture was evoked below 25 degrees C.2. At both normal and low temperatures, the tissue had cable-like properties. The length constant was reduced from 1.82 mm (36 degrees C) to 1.54 mm (20 degrees C) and to 1.04 mm (10 degrees C). On the other hand, the time constant of the membrane calculated from the cable equations was prolonged by lowering the temperature from 157 msec (36 degrees C) to 257 msec (20 degrees C) and to 508 msec (10 degrees C). The effective resistance of the membrane was increased to 1.8 times at 20 degrees C and to 2.9 times the control value at 10 degrees C.3. From the changes in various parameters of the membrane at low temperature, an increase in the longitudinal resistance of the tissue was postulated.4. The possible mechanisms of action of low temperature on the electrical properties of the smooth muscle of the urinary bladder were discussed in relation to those of the taenia coli and stomach, especially on the effects of low temperature on the sequestered Ca in the cell.

Action Potentials↗
PubMed1974

The rapid cooling contracture of toad cardiac muscles.

The effect of rapid cooling on the mechanical activities of the cardiac muscles of the Japanese toad was examined. 1. The mechanical responses produced by rapid cooling (23 leads to 0 degrees C) in both auricular and ventricular muscle preparations were composed of an immediate effect (phasic contraction) and a delayed effect (tonic contraction). The immediate effect was blocked by TTX, but the delayed effect was not affected by TTX and Mn. 2. The tonic contraction of the delayed effect produced by rapid cooling was potentiated in Na-deficient Ringer solution in which an equivalent amount of NaC1 was substituted for Tris-C1. The relationship between the relative tension of the delayed effect produced by rapid cooling and the ratio of [Ca2+]/[Na+]2 showed an S-shaped curve. 3. Generation of tension development of the delayed effect produced by rapid cooling was obviously dependent upon the extracellular Ca concentrations. There waa an S-shaped relationship between the relative tension of the delayed effect and pCa in the extracellular medium. 4. In the test solution containing Ca less than pCa8.0, no tension development of the delayed effect was observed. However, the rapid cooling contracture was strongly elicited by application of caffeine (caffeine-RCC). 5. The caffeine-RCC was also observed in the presence of 100 mM KC1. 6. From the results of the present study, it was considered that, even though the Ca influx was abolished, the contraction of the cardiac muscle could be produced by another mechanism, probably due to increase of myoplasmic Ca released by raid cooling from the cell membrane itself and the sarcoplasmic reticulum.

Animals↗
PubMed1972

[Colposcopy].

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Carcinoma, Squamous Cell↗