Stimulation of unitary T-type Ca2+ channel currents by calmodulin-dependent protein kinase II

Paula Q. Barrett, Hong-Kai Lu, Roger Colbran, Andrew Czernik, Joseph J. Pancrazio
2000 American Journal of Physiology - Cell Physiology  
Stimulation of unitary T-type Ca 2ϩ channel currents by calmodulin-dependent protein kinase II. Am J Physiol Cell Physiol 279: C1694-C1703, 2000.-The effect of Ca 2ϩ /calmodulin-dependent protein kinase II (CaMKII) stimulation on unitary low voltage-activated (LVA) T-type Ca 2ϩ channel currents in isolated bovine adrenal glomerulosa (AG) cells was measured using the patch-clamp technique. In cell-attached and insideout patches, LVA channel activity was identified by voltagedependent
more » ... pendent inactivation and a single-channel conductance of ϳ9 pS in 110 mM BaCl 2 or CaCl 2 . In the cell-attached patch, elevation of bath Ca 2ϩ from 150 nM to 1 M raised intracellular Ca 2ϩ in K ϩ -depolarized (140 mM) cells and evoked an increase in the LVA Ca 2ϩ channel probability of opening (NP o ) by two-to sixfold. This augmentation was associated with an increase in the number of nonblank sweeps, a rise in the frequency of channel opening in nonblank sweeps, and a 30% reduction in first latency. No apparent changes in the single-channel open-time distribution, burst lengths, or openings/burst were apparent. Preincubation of AG cells with lipophilic or peptide inhibitors of CaMKII in the cellattached or excised (inside-out) configurations prevented the rise in NP o elicited by elevated Ca 2ϩ concentration. Furthermore, administration of a mutant recombinant CaMKII␣ exhibiting cofactor-independent activity in the absence of elevated Ca 2ϩ produced a threefold elevation in LVA channel NP o . These data indicate that CaMKII activity is both necessary and sufficient for LVA channel activation by Ca 2ϩ . glomerulosa cells; low voltage-activated channels
doi:10.1152/ajpcell.2000.279.6.c1694 pmid:11078683 fatcat:dd7mq6vq4vakzj336chi7ovzj4