Different expressions of large-conductance Ca2+-activated K+ channels in the mouse renal cortex and hippocampus during postnatal development.

: Large-conductance Ca(+)-activated K(+) (BKCa) channels are widely distributed in a variety of cells and play a pivotal and specific role in many pathophysiological conditions. However, the function of BK(Ca) channels in the kidney cortex and hippocampus during the postnatal development has not received attention. In this study, to elucidate the role of BK(Ca) channels during the development, it is essential to establish the location and quantitation of expression of BK(Ca). The expressions of BK(Ca) were detected in the kidney and hippocampus on postnatal days (P) 1, 3, 5, 7, 14, 21, 28, and 49 by immunohistochemical and Western blot analysis. Our results showed that expressions of BK(Ca) channels were found in tubules and corpuscles at all time points. The expression was also observed at all developmental stages of the renal corpuscles, such as comma-shaped body, S-shaped body, renal corpuscles of stage III, and renal corpuscles of stage IV. During the development, the expression of BK(Ca) channels was decreased and the most prominent change of BK(Ca) protein level appeared between P14 and P21. In contrast, BK(Ca) channels were expressed in all regions of the hippocampus at every time point with the level increasing during the early development (P1 to P14). The findings of the present study suggest that BKCa channels play an important role during the postnatal development in both the renal cortex and hippocampus.