Characterization of Intermediate Conductance K<SUP>⁢</SUP> Channels in Submandibular Gland Acinar Cells
Characterization of Intermediate Conductance K<SUP>⁢</SUP> Channels in Submandibular Gland Acinar Cells
- 대한생리학회-대한약리학회
- The Korean Journal of Physiology & Pharmacology
- 제6권 제6호
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2002.01305 - 309 (5 pages)
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<P> There are some evidences that K<SUP>⁢</SUP> efflux evoked by muscarinic stimulation is not mainly mediated by large conductance K<SUP>⁢</SUP> (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<SUP>⁢</SUP> 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<SUP>⁢</SUP> 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<SUP>⁢ </SUP>(IK) channels, which were observed from all 6 cells we studied. When we increased Ca<SUP>2⁢</SUP> concentration of the bath solution in inside-out mode, the IK channel activity was greatly increased, suggesting this channel is Ca<SUP>2⁢</SUP> sensitive. We next examined the effect of carbachol (CCh) and isoproterenol on the activity of the IK channels. 10<SUP>⁣5 </SUP>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<SUP>⁣5 </SUP>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 β- 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.
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