Characterization of Intermediate Conductance K+ Channels in Submandibular Gland Acinar Cells.
- Author:
Sung Man CHO
1
;
Zheng Gen PIAO
;
Yoon Bae KIM
;
Joong Soo KIM
;
Kyungpyo PARK
Author Information
1. Department of Physiology, College of Dentistry, Seoul National University and Dental Research Institute, Seoul , Korea. kppark@snu.ac.kr
- Publication Type:Original Article
- Keywords:
Submandibular;
Patch clamp;
IK channels;
Carbachol;
Isoproterenol
- MeSH:
Acinar Cells*;
Adrenergic Agonists;
Animals;
Baths;
Carbachol;
Isoproterenol;
Large-Conductance Calcium-Activated Potassium Channels;
Rats;
Salivary Glands;
Submandibular Gland*
- From:The Korean Journal of Physiology and Pharmacology
2002;6(6):305-309
- CountryRepublic of Korea
- Language:English
-
Abstract:
There are some evidences that K+ efflux evoked by muscarinic stimulation is not mainly mediated by large conductance K+ (BK) channels in salivary gland. In this experiment, we therefore characterised non BK channels in rat submandibular gland acinar cells and examined the possibility of agonist effect on this channel using a patch clamp technique. Two types of K+ channels were observed in these cells. BK channels were observed in 3 cells from total 6 cells and its average conductance was 152+/- 7 pS (n=3). The conductance of the another types of K+ channel was estimated as 71+/-7 pS (n=6). On the basis of the conductance of this channel, we defined this channel as intermediate conductance K+ (IK) channels, which were observed from all 6 cells we studied. When we increased Ca2+ concentration of the bath solution in inside-out mode, the IK channel activity was greatly increased, suggesting this channel is Ca2+ sensitive. We next examined the effect of carbachol (CCh) and isoproterenol on the activity of the IK channels. 10(-5) M isoproterenol significantly increased the open probability (Po) from 0.08+/-0.02 to 0.21+/-0.03 (n=4, P<0.05). Application of 10(-5) M CCh also increased Po from 0.048+/-0.03 to 0.55+/-0.33 (n=5, P<0.05) at the maximum channel activity. The degree of BK channel activation induced by the same concentration of CCh was lower than that of IK channels; Po value was 0.011+/-0.003 and 0.027+/-0.005 in control and during CCh stimulation (n=3), respectively. The result suggests that IK channels exist in salivary acinar cells and its channel activity is regulated by muscaricinic and beta- adrenergic agonist. We conclude that IK channels also play a putative role in secretion as well as the BK channels in rat submandibular gland acinar cells.
