K+ channels in mucous cells isolated from the rat sublingual gland

Abstract

The basolateral, voltage dependent K+ channels of mucous cells dissociated from rat sublingual gland were studied using the patch-clamp technique. In the cell-attached mode, two typed of K+ channels could be observed in these cells. One had a large conductance of 222±7 ps(n=3). Acetylcholine (ACH; 10-5 M) activated both K+ channels by increasing the open probability (Po). Open probability for the large conductance channels by increased frin 0.18 in the control slution to a maximum value of 0.85 after addition of Ach. Whereas, Po for the small conductance channels increased from 0.002 in the control solution to a maximum value of 0.31. K+ channel activation by 10-5M Ach was observed in 2 other mucous cells. When the osmolarity of bath solution was reduced to 60% of control, both large and small conductance K+ channels were activated. Open probability for the large and small conductance K+ channels increased significantly (P<0.05) from 0.006±0.001 (n=4) and 0.002±0.001 (n=4) in the control solution to a aximum value of 0.30±0.04 and 0.12±0.03 in the hypotonic solution, respectively. It is concluded that both K+ channels may play a crucial role in secretion induced by muscarinic receptor activation and in regulatory volume decrease (RVD).