Roles of Ca2+ activated K+ conductances on spontaneous firing patterns of isolated rat medial vestibular nucleus neurons

To investigate the contributions of intrinsic membrane properties to the spontaneous activity of medial vestibular nucleus (MVN) neurons, we assessed the effects of blocking large and small calcium-activated potassium channels by means of patch clamp recordings. Almost all the MVN neurons recorded in neonatal (P13~P17) rat were shown to have either a single deep after-hyperpolarization (AHP; type A cells), or an early fast and a delayed slow AHP (type B cells). Among the recorded MVN cells, immature action potential shapes were found. Immature type A cell showed single uniform AHP and immature B cell showed a lack of the early fast AHP, and the delayed AHP was separated from the repolarization phase of the spike by a period of isopotentiality. Application of apamin and charybdotoxin (CTX), which selectively block the small and large calcium-activated potassium channels, respectively, resulted in significant changes in spontaneous firings. In both type A and type B cells, CTX (20 nM) resulted in a significant increase in spike frequency but did not induce bursting activity. By contrast, apamin (300 nM) selectively abolished the delayed slow AHP and induced bursting activity in type B cells. Apamin had no effect on the spike frequency of type A cells. These data suggest that there are differential roles of apamin and CTX sensitive potassium conductances in spontaneous firing patterns of MVN neurons, and these conductances are important in regulating the intrinsic rhythmicity and excitability.

The related factors of pregnant women's acceptance of natural family planning in a certain area

BACKGROUND: It is reported that approximately 10.7% of Korean reproductive women use rhythm method to avoid pregnancy, which is higher in comparison to other countries. However, few surveys on practicing natural family planning methods have been done and awareness of it is also very(low). Our study examined women's interest and related factors in using natural family planning either to become pregnant or to avoid it. METHODS: A questionnaire was given to 1,700 women, ages 18 to 50, who visited general hospitals in Seoul and Kyounggido for health examination from the months beginning July and ending September in 1998. RESULTS: Of the 604 answered questionnaires, 361 were from women who were potentially fertile. Of these women 45.4% indicated that they would likely use natural family planning in the future to avoid pregnancy, and 30.5% indicated that they would likely use natural family planning in the future to become pregnant. Past use of any method of natural family planning to avoid pregnancy was associated with interest in future use of modern methods of natural family planning to avoid pregnancy. Age under 30, past use of natural family planning to become pregnant and the possible desire for future pregnancy were associated with interest in future use of natural family planning to conceive. CONCLUSION: Interest in future use of natural family planning is associated with past use of natural family planning including other factors. Many women who have not used natural family planning showed interest in using natural family planning, either to avoid pregnancy or to conceive. Therefore, clinicians should include modern natural family planning method in all of their discussions with women about family planning options.