Journal
AMERICAN JOURNAL OF PHYSIOLOGY-REGULATORY INTEGRATIVE AND COMPARATIVE PHYSIOLOGY
Volume 292, Issue 5, Pages R2100-R2112Publisher
AMER PHYSIOLOGICAL SOC
DOI: 10.1152/ajpregu.00779.2006
Keywords
large-conductance K-Ca channel; small-conductance K-Ca channel; cholinergic; purinergic
Categories
Funding
- NIDDK NIH HHS [K08 DK065759, R37 DK049430, R01 DK049430, DK65759, R37 DK049430-12, DK49430] Funding Source: Medline
Ask authors/readers for more resources
Spontaneous bladder contractions (SBCs) in the neonatal rat urinary bladder change from a high-amplitude, low-frequency pattern to a low-amplitude, high-frequency pattern during the first 6 wk of life. Understanding the mechanism of this developmental change may provide insights into the causes of bladder overactivity in adults. In vitro whole bladder preparations from Sprague-Dawley rats were used to study the modulation of SBCs by calcium-activated potassium channels (K-Ca) and electrical field stimulation from 3 days to 6 wk of life. SBCs in 3-day-old bladders were unmasked by treatment with iberiotoxin (100 nM), an inhibitor of large conductance K-Ca (BK) channels, or aparnin (100 nM), an inhibitor of small conductance K-Ca, (SK) channels. Iberiotoxin significantly increased the magnitude of SBCs at 2-3 wk, whereas aparnin was only effective at 6 wk. In 1-2 wk bladders, exposure to room temperature Krebs solution decreased SBCs. This decrease was reversed by activating intramural nerves with electrical field stimulation. The effect of electrical field stimulation was inhibited by atropine (1 mu M), suramin (10 mu M), or pretreatment with tetrodotoxin (1 mu M) but was not reversed by tetrodotoxin applied after electrical field stimulation. BK-alpha mRNA increased threefold, and BK-alpha protein increased fivefold from 3 days to 6 wk. These data suggest that BK channels play an important role in the regulation of SBCs in the neonatal bladder and that both increased BK channel activity, as well as changes in smooth muscle sensitivity to locally released neurotransmitters contribute to the downregulation of SBCs during early postnatal development.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available