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Ca(v)1.3 channels produce persistent calcium sparklets, but Ca(v)1.2 channels are responsible for sparklets in mouse arterial smooth muscle.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Navedo, Manuel F. Amberg, Gregory C. Westenbroek, Ruth E. Sinnegger-Brauns, Martina J. Catterall, William A. Striessnig, Jörg Santana, L. Fernando |
| Copyright Year | 2007 |
| Abstract | Ca(2+) sparklets are local elevations in intracellular Ca(2+) produced by the opening of a single or a cluster of L-type Ca(2+) channels. In arterial myocytes, Ca(2+) sparklets regulate local and global intracellular Ca(2+). At present, the molecular identity of the L-type Ca(2+) channels underlying Ca(2+) sparklets in these cells is undetermined. Here, we tested the hypotheses that voltage-gated calcium channel-alpha 1.3 subunit (Ca(v)1.3) can produce Ca(2+) sparklets and that Ca(v)1.2 and/or Ca(v)1.3 channels are responsible for Ca(2+) sparklets in mouse arterial myocytes. First, we investigated the functional properties of single Ca(v)1.3 channels in tsA201 cells. With 110 mM Ba(2+) as the charge carrier, Ca(v)1.3 channels had a conductance of 20 pS. This value is similar to that of Ca(v)1.2 and native L-type Ca(2+) channels. As previously shown for Ca(v)1.2 channels, Ca(v)1.3 channels can operate in two gating modes characterized by short and long open times. Expressed Ca(v)1.3 channels also produced Ca(2+) sparklets. Ca(v)1.3 sparklets had properties similar to those produced by Ca(v)1.2 and native L-type channels, including quantal amplitude, dihydropyridine sensitivity, bimodal gating, and dual-event duration times. However, the voltage dependencies of conductance and steady-state inactivation of the Ca(2+) current (I(Ca)) in arterial myocytes were similar to those recorded from cells expressing Ca(v)1.2 but not Ca(v)1.3 channels. Furthermore, nifedipine (10 microM) eliminated Ca(2+) sparklets in wild-type myocytes but not in myocytes expressing dihydropyridine-insensitive Ca(v)1.2 channels. Accordingly, Ca(v)1.3 transcript and protein were not detected in isolated arterial myocytes. We conclude that although Ca(v)1.3 channels can produce Ca(2+) sparklets, Ca(v)1.2 channels underlie I(Ca), Ca(2+) sparklets, and hence dihydropyridine-sensitive Ca(2+) influx in mouse arterial myocytes. |
| Starting Page | 1339 |
| Ending Page | 1349 |
| Page Count | 11 |
| File Format | PDF HTM / HTML |
| PubMed reference number | 17526649 |
| Journal | Medline |
| Volume Number | 293 |
| Issue Number | 3 |
| Alternate Webpage(s) | http://ajpheart.physiology.org/content/ajpheart/293/3/H1359.full.pdf |
| Journal | American journal of physiology. Heart and circulatory physiology |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
