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The effects of low temperature (36-10° 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° C, depolarized the membrane from -37 to -33 and to -25 mV respectively. Spontaneous and propagated spike activity ceased completely at below 20° C but evoked spikes were occasionally observed at 10° C. A sustained contracture was evoked below 25° C.
2. At both normal and low temperatures, the tissue had cable-like properties. The length constant was reduced from 1·82 mm (36° C) to 1·54 mm (20° C) and to 1·04 mm (10° 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° C) to 257 msec (20° C) and to 508 msec (10° C). The effective resistance of the membrane was increased to 1·8 times at 20° C and to 2·9 times the control value at 10° 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.
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K. Sugaya and W. C. de Groat Influence of temperature on activity of the isolated whole bladder preparation of neonatal and adult rats Am J Physiol Regulatory Integrative Comp Physiol, January 1, 2000; 278(1): R238 - R246. [Abstract] [Full Text] [PDF] |
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