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KCI등재 학술저널

Characterization of Intermediate Conductance K<SUP>&#8290;</SUP> Channels in Submandibular Gland Acinar Cells

Characterization of Intermediate Conductance K<SUP>&#8290;</SUP> Channels in Submandibular Gland Acinar Cells

<P> There are some evidences that K<SUP>&#8290;</SUP> efflux evoked by muscarinic stimulation is not mainly mediated by large conductance K<SUP>&#8290;</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>&#8290;</SUP> channels were observed in these cells. BK channels were observed in 3 cells from total 6 cells and its average conductance was 152&#8273;7 pS (n=3). The conductance of the another types of K<SUP>&#8290;</SUP> channel was estimated as 71&#8273;7 pS (n=6). On the basis of the conductance of this channel, we defined this channel as intermediate conductance K<SUP>&#8290; </SUP>(IK) channels, which were observed from all 6 cells we studied. When we increased Ca<SUP>2&#8290;</SUP> concentration of the bath solution in inside-out mode, the IK channel activity was greatly increased, suggesting this channel is Ca<SUP>2&#8290;</SUP> sensitive. We next examined the effect of carbachol (CCh) and isoproterenol on the activity of the IK channels. 10<SUP>&#8291;5 </SUP>M isoproterenol significantly increased the open probability (Po) from 0.08&#8273;0.02 to 0.21&#8273;0.03 (n=4, P<0.05). Application of 10<SUP>&#8291;5 </SUP>M CCh also increased Po from 0.048&#8273;0.03 to 0.55&#8273;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&#8273;0.003 and 0.027&#8273;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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