Transient intracellular calcium movement coupled with mechanical activity of smooth muscle.

We have shown previously(J.J.P.35：1079，1985)that，intracellular free Ca in smooth muscle cells(Guina Pig Jejunum)increased transiently upon stimulation followed by the mechanical response.We explored this study to the single cell using Fura2.The isolated cell was obtained from taenia coli of guiea pig according to the method described by Momose&Gomi in1979(J.Pharmaco dynamics 1：184)。Fura2was loaded into the cell by incubating the sample in HEPES buffer containing Fura2AM for 30min at 37°C.The photomultiplier was set to recieve the emission(470 Nm)light from only one cell on the stage of microscope.Upon application of electric pulse，intensity of fluorecence light from the muscle begun to increase immedately after application of stimulus reaching to the maximum within one sec and returned to the originiginal level afsec。Concentration of intracellular freeCa was estimated as approximately&lt；10^(-7)&gt；M and the order of&lt；10^(-6)&gt；M，at rest and the maximum，respectively。The rate of light intensity change was faster than that observed previously in the tissue preparation.The speed of contraction following the stimulation was much slower than that of intracellular Ca transient。The results obtained here，together with previous one，suggest that intracellulary stored Ca may play certain role for the mechanical activation of the smooth muscle cell.

We have shown previously(J.J.P.35:1079,1985) that, intracellular free Ca in smooth muscle cells(guina pig jejunum) increased transiently upon stimulation followed by the mechanical response. We explored this study to the single cell using Fura 2.The isolated cell was obtained from taenia coli of guiea pig according to the method described by Momose & Gomi in 1979(J.Pharmaco dynamics 1:184). Fura2 was loaded into the cell by incubating the sample in HEPES buffer containing Fura 2AM for 30 min at 37゜C. The photomultiplier was set to recieve the emission(470nm) light from only one cell on the stage of microscope.Upon application of electric pulse, intensity of fluorecence light from the muscle begun to increase immedately after application of stimulus reaching to the maximum within one sec and returned to the original level after 2 sec. Concentration of intracellular freeCa was estimated as approximately <10^(-7)> M and the order of <10^(-6)> M,at rest and the maximum,respectively. The rate of light intensity change was faster than that observed previously in the tissue preparation. The speed of contraction following the stimulation was much slower than that of intracellular Ca transient. The results obtained here,together with previous one,suggest that intracellulary stored Ca may play certain role for the mechanical activation of the smooth muscle cell.