T-type channels contribute to which feature in SA and AV nodal cells?

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Multiple Choice

T-type channels contribute to which feature in SA and AV nodal cells?

Explanation:
T-type calcium channels provide a low-threshold inward Ca2+ current that helps drive the slow, spontaneous depolarization during diastole in SA and AV nodal cells. This early phase 4 pacemaker current gradually depolarizes the cell toward the threshold, setting the pace of automaticity. In nodal tissue, the upstroke and plateau involve mainly calcium entry through L-type channels, but the specific feature tested here is the contribution of T-type channels to the initial, negative-potential phase 4 depolarization that enables rhythmic firing.

T-type calcium channels provide a low-threshold inward Ca2+ current that helps drive the slow, spontaneous depolarization during diastole in SA and AV nodal cells. This early phase 4 pacemaker current gradually depolarizes the cell toward the threshold, setting the pace of automaticity. In nodal tissue, the upstroke and plateau involve mainly calcium entry through L-type channels, but the specific feature tested here is the contribution of T-type channels to the initial, negative-potential phase 4 depolarization that enables rhythmic firing.

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