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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Calcium, Cell Size, Colon, Humans, Hypotonic Solutions, Intermediate-Conductance Calcium-Activated Potassium Channels, Intestinal Mucosa, Patch-Clamp Techniques, Potassium Channels, Calcium-Activated.
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Does hypotonic stress activate an intermediate conductance K+ channel in human colonic crypt cells? Context: To investigate the effect of hypotonic stress on human colonic crypts cells in terms of ion channel activity and intracellular Ca2+ concentration. Single crypts were isolated from biopsies taken during colonoscopy. The patch clamp technique was used (in the cell-attached mode) to observe the activity of ion channels during hypotonic stress. Calcium measurements were made using the fluophores Fluo 3 or 4. The intermediate conductance (29 pS), Ca2+ -sensitive, K+ channel (also known as KCNN4) previously described (Sandle et al. 1994) was seen in 54 of 149 patches (36%) when the crypts were bathed in normal extracellular solution (290 mOsm kg(-1)). Forty-one patches could be used for further analysis. Activation of one or several 29 pS channels was seen in 15 of 41 patches (39%) after 30 s to 4 min of exposure to hypotonic solution (160 mOsm kg(-1)). The open probability increased from 0.0043 in control solution to 0.44 at 5 min of hypotonic stress. When the crypts were exposed to hypotonic solution, an increase in intracellular Ca2+ could be seen. The increase in intracellular Ca2+ emanates mainly from intracellular stores.
assistant
The 29 pS K+ channel takes part in volume regulation in human colonic crypt cells. The activation of this channel is mediated through an increase in intracellular Ca2+. Final Decision: yes