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THE INHIBITORY ACTION OF OESTRADIOL‐17‐β AND PROGESTERONE ON VENOUS SMOOTH MUSCLE
Author(s) -
McCALDEN T.A.
Publication year - 1975
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1975.tb07348.x
Subject(s) - endocrinology , medicine , gestation , inhibitory postsynaptic potential , contraction (grammar) , pregnancy , portal vein , vein , fetus , chemistry , biology , genetics
1 The in vitro action of oestradiol‐17‐β (0.1, 1.0 and 10.0 μg/ml) and progesterone (0.1, 1.0 and 10.0 μg/ml) on the spontaneous activity of the portal veins in female rats at different stages of gestation was studied. 2 Progesterone caused the spontaneous mechanical activity in the rat portal vein to decrease in amplitude and increase in frequency. This action was dose‐dependent and the sensitivity of the tissue decreased throughout pregnancy. 3 Oestradiol‐17‐β had a biphasic effect on spontaneous mechanical activity in the rat portal vein. At 0.1 μg/ml the vessel was stimulated while a similar effect to progesterone occurred with higher concentrations. The tissue was more sensitive to oestradiol at 7 days of gestation than at either the 10‐14 or 17‐21 day periods of gestation. 4 These effects of oestradiol and progesterone were still seen after blockade of the β‐adrenoceptors. 5 Hydrocortisone (10 μg/ml) had no inhibitory effect on the spontaneous mechanical activity of the vein. 6 The veins from the 17‐21 days pregnant animals showed a smaller amplitude of contraction than comparable non‐pregnant females.