Open AccessEffects of Li-substitution on high-K induced contractions of various smooth muscle tissues in the guinea-pig.
Author(s) -
Tadashi Kishimoto,
Norimoto Urakawa
Publication year - 1982
Publication title -
japanese journal of pharmacology/japanese journal of pharmacology
Language(s) - English
Resource type - Journals
eISSN - 1347-3506
pISSN - 0021-5198
DOI - 10.1254/jjp.32.563
Subject(s) - taenia coli , contraction (grammar) , chemistry , ileum , guinea pig , aorta , biophysics , vascular smooth muscle , inhibitory postsynaptic potential , smooth muscle , medicine , endocrinology , biochemistry , biology
The effects of partial Li-substitution for external Na in the medium on contraction, cellular Li concentration, and 45Ca uptake of various smooth muscle tissues depolarized by a high-K (62.7 mM) solution were studied. In the taenia coli and ileum isolated from the guinea-pig, Li-substitution (23.7 mM-59.4 mM) increased the cellular Li concentration and strongly inhibited the K-contraction. A good correlation between cellular Li concentration and inhibition of tension was obtained in both the taenia coli and ileum. In the portal vein and uterus, Li-substitution inhibited K-concentration in correlation with Li-accumulation although the inhibitory effect was weaker than those obtained with the taenia coli and ileum. In the aorta, Li-substitution did not affect K-concentration in spite of the accumulation of Li. The inhibitory effects of Li-substitution in all the tissues except the aorta were antagonized by an increase in external Ca, and the inhibition was accompanied by a decrease in cellular 45Ca content. Although there is a tissue-specific difference, a possibility exists that excess cellular Li inhibits the K-induced Ca influx. The K-induced Ca influx in the aorta seems to be almost insensitive to the inhibitory effect of cellular Li.