Summary
Intra- and extracellular measurements of electrical activity were recorded simultaneously with tension development from isolated preparations of taenia coli, portal vein, stomach and ureter of the guinea-pig. Iproveratril (verapamil) inhibits electrical and mechanical activity in parallel in spontaneously active preparations of taenia coli and portal vein. Spike discharges and second-rhythm (SR) oscillations are both suppressed in the electrical activity. In portal vein, the relatively weak basic organ specific rhythm (BOR) of this tissues is also suppressed. The minute-rhythm (MR) appears less sensitive or resistant to iproveratril. In ureter and antrum preparations of the stomach there is an additional iproveratril resistant component: the basic electrical process of stomach and ureter peristalsis which, in the classification of smooth muscle rhythms, belongs to the type BOR. The superimposed spike potentials of the antrum and the spike-like oscillations of the ureter action potential are inhibited similarly as are the spike potentials in taenia coli and portal vein. The similarity between the iproveratril effects and the effect of Ca-deprivation indicates a Ca-antagonistic action of iproveratril. Conclusions concerning the hypothesis of “Ca-spikes” in smooth muscle are discussed.
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Golenhofen, K., Lammel, E. Selective suppression of some components of spontaneous activity in various types of smooth muscle by iproveratril (verapamil). Pflugers Arch. 331, 233–243 (1972). https://doi.org/10.1007/BF00589130
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DOI: https://doi.org/10.1007/BF00589130