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The precise regulatory mechanisms of cyclic oviductal contraction in the cow are unclear. The purpose of this study was to evaluate the effect of luteinizing hormone (LH), steroids, prostaglandins (PGs) and peptides on the oviductal contraction and secretion of PGs and endothelin (ET-1). In addition, the cyclic expression of mRNA for ET-1 and its receptors (ET-R) was evaluated by reverse transcription-polymerase chain reaction (RT-PCR). In the in vitro microdialysis study, an infusion of LH alone or in combination with progesterone (P 4 ), estradiol-17 (E 2 ) and/or ET-1 stimulated pronounced release of PGE 2 , PGF 2 and ET-1 in the oviducts from cows in the follicular and postovulatory phases. The addition of LH, LH+P 4 +E 2 and/or ET-1 to the medium increased the amplitude of oviductal contraction. However, oxytocin (OT) completely blocked the responses of oviductal secretion and contraction. In contrast, these substances did not show any effect in the oviducts from cows in the mid luteal phase. Similar expression patterns of mRNA encoding for ET-R type A and type B were found, which were highest during the postovulatory phase, lower during the luteal phase, with the lowest expression during the follicular phase. We suggest that the preovulatory LH surge, together with increasing E 2 levels from the Graafian follicle and a basal P 4 from regressing corpora lutea (CL), stimulates maximum oviductal production of PG and ET-1, resulting in oviductal contraction for a rapid transport of gametes. OT released from the newly-formed CL may block these mechanisms, and slow contractions for transport of the embryo to the uterus.

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Abstract. In mouse intestinal smooth muscle cells held at −50 mV, carbachol evoked an atropine-sensitive inward current in the intracellular presence of Cs + . The current response consisted of an initial peak followed by a smaller plateau component on which oscillatory currents frequently arose. Results from various experimental procedures indicated that the inward current is a muscarinic receptor-operated cationic current (mI cat ) sensitive to cytosolic Ca ] i buffered to 100 nM, the mI cat response to cumulative carbachol applications was inhibited competitively by an M 2 -selective antagonist but non-competitively by an M 3 -selective one. Also it was severely reduced by pertussis toxin (PTX) treatment or a phospholipase C (PLC) inhibitor. Comparative analysis of mI cat in mouse and guinea-pig intestinal myocytes indicated that the underlying channels resemble between those myocytes in agonist sensitivity, current-voltage relationship, and unitary conductance. The results suggest that in mouse intestinal myocytes, mI cat arises mainly via an M 2 / M 3 synergistic mechanism involving PTX-sensitive G-proteins and PLC activity in the absence of current modulation by [Ca 2+ ] i changes, as described for guinea-pig ileal mI cat . The channels underlying mI cat are also indistinguishable in gating properties between both types of myocytes.

Although the antioxidant properties of green, oolong, and black teas have been well studied, antioxidant activity has not been examined in roasted tea. Therefore, in the current studies, we investigated the antioxidant activity of roasted tea in comparison with those of green, oolong, and black teas. Using water extracts of the various teas, we examined the total phenolic content as well as the antioxidant activities, including the reducing power, the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity, and the inhibition of hemolysis caused by 2,2'-azo-bis(2-amidinopropane) dihydrochloride (AAPH)-induced lipid oxidation in erythrocyte membranes. The roasted tea contained lower levels of total phenolics than green, oolong, or black tea (green tea > oolong tea > black tea > roasted tea). The relative reducing power and DPPH scavenging activity decreased in the following order: green tea > roasted tea > oolong tea > black tea. Also, green tea was more effective against AAPH-induced erythrocyte hemolysis than other teas (green tea>roasted tea = oolong tea = black tea). These results suggest that roasted tea is beneficial to health, in humans, because of its high antioxidant activity.