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Indian Journal of Experimental Biology (IJEB) >
IJEB Vol.44 [2006] >
IJEB Vol.44(01) [January 2006] >
| Title: | Hypothyroid state reduces calcium channel function in 18-day pregnant rat uterus |
| Authors: | Parija, S C
Mishra, S K
Raviprakash, V |
| Keywords: | Calcium
Hypothyroidism
Pregnancy
Uterus |
| Issue Date: | Jan-2006 |
| Publisher: | CSIR |
| Abstract: | Hypothyroidism
significantly reduced the mean amplitude and increased the mean frequency of
spontaneous rhythmic contractions in 18day pregnant rat uterus. Nifedipine (10-12-10-9
M) and diltiazem (10-10-10-6M) caused concentration related
inhibition of the myogenic responses of the uterine strips obtained from both
pregnant and hypothyroid state. However, nifedipine was less potent (IC50:2.11×10-11 M) in
pregnant hypothyroid state as compared to pregnant control (IC50:
3.1×10-12M). Similarly, diltiazem was less potent
(IC50 : 3.72×10-9
M) in inhibiting the uterine
spontaneous contractions in hypothyroid than in pregnant rat uterus (IC50:5.37×10-10 M). A similar decrease in the sensitivity to
nifedipine and diltiazem for reversal of K+ (100 mM)–induced tonic contraction and K+-stimulated
45Ca2+ influx was observed with these calcium channel
antagonists in uterus obtained from hypothyroid pregnant rats compared to the
controls. Nifedipine–sensitive influx of 45Ca2+-stimulated
either by K+ (100 mM) or
by Bay K8644 (1,4-dihydro-2,6-methyl-5-nitro-4-[2'-(tri-fluromethyl)phenyl]-3-pyridine carboxylic acid methyl ester)
(10-9 M) was significantly
less in uterine strips from hypothyroid rats compared to controls. The results
suggest that the inhibition of uterine rhythmic contractions may be
attributable to a reduction in rat myometrial Ca2+ channel function
in the hypothyroid state. |
| Page(s): | 19-27 |
| ISSN: | 0975-1009 (Online); 0019-5189 (Print) |
| Source: | IJEB Vol.44(01) [January 2006]
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