Effects of ProstagIand in F2a on the Spontaneous Contractions and Electrical Activities in the Circular Smooth MuscIe of the Guinea-Pig Stomach

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Kim, Sung Joon; Lee, Sang Jin; Yoon, Byung Chul; Kim, Ki Whan

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Seoul National University College of Medicine
Seoul J Med, Vol.34 No.2, pp. 83-97
PGF2aSmooth muscleSlow waveIonic current
Effects of PGF2a and indomethacin on the mechanical and electrical
membrane properties of guinea-pig antral smooth muscle were studied using
microeletrodes and tension recording technique and whole cell patch clamp
technique. In this tissue, indomethacin inhibited the contractility and such an
effect was reversed by PGF2a. PGF2a increased spontaneous contractions
potently and the frequency and amplitudes of slow waves were also enhanced.
PGF2a-induced contractions were not abolished by the pretreatment with
nifedipine or by the nominal Ca2+-free condition but were abolished by
pretreatment with La3+ or absolute Ca2+-free condition. Ionic currents were also
measured by whole cell voltage clamp technique. PGF2a increased the size of
voltage operated Ca2+ inward currents, and Ca-dependent K+ outward currents,
but had no effect on sustained outward currents. From the above results, it is
assumed that PGF2 a acts as an endogenous prostaglandin in the gastric antrum
of the guinea-pig. PGF2a has promoting effects on electrical activities and such
effects seem to contribute to the increase of contraction, but the greatest part of
the increase of contraction is due to receptor-mediated increase of [Ca2+]i.
Several possible mechanisms were suggested for the receptor-mediated [Ca2+]i
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College of Medicine/School of Medicine (의과대학/대학원)Dept. of Medicine (의학과)The Seoul Journal of MedicineThe Seoul Journal of Medicine Vol. 34 No.2 (1993)
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