Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P01178 (oxytocin)
 15,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. The effect of caffeine on mechanical activity was studied in pregnant rat myometrium. 2. In muscle cells with intact plasmalemmae, caffeine (0.1-50 mM) produced no contraction whatever the experimental conditions. 3. Caffeine (0.1-10 mM) inhibited, in a concentration-dependent manner, contractions induced by electrical stimulation, potassium-rich (60 mM K+) solution, sodium-free solution or oxytocin (22.5 nM). 4. In Ca2(+)-free solution, various substances (oxytocin, sodium orthovanadate and prostaglandin E2) evoked sustained contractions that were suppressed by caffeine (5-10 mM). When caffeine (greater than 5 mM) was applied during Ca2(+)-loading of the tissue (2.1 mM Ca2+, 5 min) in the presence of a K(+)-rich solution, the subsequent transient contraction induced by a short application (10s) of oxytocin (22.5 nM) in Ca-free solution was reduced (63 +/- 3.5% reduction for 20 mM caffeine, n = 4). 5. In saponin-skinned strips, application of caffeine (5-10 mM) during loading of the Ca2(+)-store increased the subsequent contraction induced by myo-inositol 1,4,5 trisphosphate (IP3, 10 microM). Caffeine (10-30 mM) decreased calcium-activated contractions in skinned fibres lacking a functional internal Ca-store. This effect was reduced by the cyclic AMP-dependent protein kinase inhibitor Thr-Thr-Tyr-Ala-Asp-Phe-Ile-Ala-Ser-Gly-Arg-Thr-Gly-Arg-Arg-Asn-Ala-Ile- His-Asp (8 microM). 6. In conclusion, it is suggested that the inability of caffeine to cause spasm of rat myometrium is due to the absence of a caffeine-sensitive calcium-release channel in the sarcoplasmic reticulum. Relaxant effects of caffeine can be explained by mechanisms leading to a decrease in both the cytoplasmic free Ca2+ concentration and the Ca2 +-sensitivity of the contractile machinery.
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PMID:Caffeine acting on pregnant rat myometrium: analysis of its relaxant action and its failure to release Ca2+ from intracellular stores. 232 93

Brickellia paniculata has been used as spasmolytic in Mexican traditional medicine. Xanthomicrol and 3alpha-angeloyloxy-2alpha-hydroxy-13,14Z-dehydrocativic acid (AAHDD) are two of the main leaf components with antispasmodic activity. However, their mechanism of action remains unknown. An in vitro comparative study between xanthomicrol and AAHDD on rat uterus precontracted by either KCl (60 mM) or oxytocin (10 mIU/ml) was carried out to investigate the mechanism of action of these compounds on smooth muscle. Relaxant effect was measured as median inhibitory concentration (IC(50)) and maximal effect as maximal relaxant response (R(max)). Xanthomicrol was significantly more potent than AAHDD in inhibiting contractions induced by KCl 60 mM, whereas AAHDD was more potent than xanthomicrol in inhibiting contractions induced by oxytocin 10 mIU/ml. These results suggest that xanthomicrol induces a greater blocking effect on voltage-operated calcium channels than on receptor-operated gates.
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PMID:Relaxant effect of xanthomicrol and 3alpha-angeloyloxy-2alpha-hydroxy-13,14z-dehydrocativic acid from Brickellia paniculata on rat uterus. 1681 99