Abstract-The contractile responses of isolated uterine segments from 17(3-estradiol 3-benzoate-treated ovariectomized rats to acetylcholine (ACh) and high KCI in Ca-depleted modified Locke-Ringer solution on addition of CaC12 were used as

Abstract-UnderCa-depleted conditions, the contractile responses of rat vas deferens in the presence of norepinephrine were not elicited until the addition of CaC12. L-Methionine enhanced the contractile response of vas deferens in the presence of methylation blockers under these conditions. The enhancing effect of L-methionine on some other smooth muscles could not be determined because under Ca-depleted conditions, these muscles showed 60-80% of the maximal contractile response on addition of CaC12 alone. Theas findings suggested that L-methionine has an enhancing effect on contraction of the rat vas deferens as it does on rat uterine muscle.

Abstract-Acetylcholine (ACh) and high KCI-stimulated 45Ca uptake into rat uterine segments was inhibited by 3-deazaadenosine (3-DAA) plus homocysteine thiolactone (HCTL), and this inhibitory effect was attenuated by L-methionine (L Met). Ca-depleted Ringer solution in which uterine muscle had been incubated with L-Met did not enhance the contractile response of another uterine segment to ACh and high KCI in the presence of 3-DAA plus HCTL. These findings together with previous results suggest that the enhancing effect of L-Met on the contractile responses to ACh and high KCI is mainly due to an increase in Ca2+ uptake into the uterine muscle.

Abstract-The characteristics of superprecipitation of uterine myosin B from 170-estradiol-3-benzoate-treated rats and the effects of L-methionine and/or 3-deazaadenosine (3-DAA) plus homocysteine thiolactone (HCTL) on the reaction were investigated. The slope and plateau phases of the superprecipitation were dependent on ATP, calcium and magnesium. The calmodulin antagonists, tri fluoperazine and N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide, inhib

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