Coexpression of voltage-dependent calcium channels Cav1.2, 2.1a, and 2.1b in vascular myocytes

Hypertension. 2006 Apr;47(4):735-41. doi: 10.1161/01.HYP.0000203160.80972.47. Epub 2006 Feb 27.

Abstract

Voltage-dependent Ca2+ channels Cav1.2 (L type) and Cav2.1 (P/Q type) are expressed in vascular smooth muscle cells (VSMCs) and are important for the contraction of renal resistance vessels. In the present study we examined whether native renal VSMCs coexpress L-, P-, and Q-type Ca2+ currents. The expression of both Cav2.1a (P-type) and Cav2.1b (Q-type) mRNA was demonstrated by RT-PCR in renal preglomerular vessels from rats and mice. Immunolabeling was performed on A7r5 cells, renal cryosections, and freshly isolated renal VSMCs with anti-Cav1.2 and anti-Cav2.1 antibodies. Conventional and confocal microscopy revealed expression of both channels in all of the smooth muscle cells. Whole-cell patch clamp on single preglomerular VSMCs from mice showed L-, P-, and Q-type currents. Blockade of the L-type currents by calciseptine (20 nmol/L) inhibited 35.6+/-3.9% of the voltage-dependent Ca2+ current, and blocking P-type currents (omega-agatoxin IVA 10 nmol/L) led to 20.2+/-3.0% inhibition, whereas 300 nmol/L of omega agatoxin IVA (blocking P/Q-type) inhibited 45.0+/-7.3%. In rat aortic smooth muscle cells (A7r5), blockade of L-type channels resulted in 28.5+/-6.1% inhibition, simultaneous blockade of L-type and P-type channels inhibited 58.0+/-11.8%, and simultaneous inhibition of L-, P-, and Q-type channels led to blockade (88.7+/-5.6%) of the Ca2+ current. We conclude that aortic and renal preglomerular smooth muscle cells express L-, P-, and Q-type voltage-dependent Ca2+ channels in the rat and mouse.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Aorta / cytology
  • Aorta / metabolism
  • Calcium Channels, L-Type / genetics
  • Calcium Channels, L-Type / metabolism*
  • Calcium Channels, L-Type / physiology
  • Calcium Channels, N-Type / genetics
  • Calcium Channels, N-Type / metabolism*
  • Calcium Channels, N-Type / physiology
  • Cell Line
  • DNA, Recombinant
  • Fluorescent Antibody Technique
  • Genetic Variation
  • Kidney / blood supply
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Muscle, Smooth, Vascular / cytology
  • Muscle, Smooth, Vascular / metabolism*
  • Myocytes, Smooth Muscle / metabolism*
  • Patch-Clamp Techniques
  • Protein Isoforms / genetics
  • Protein Isoforms / metabolism
  • Protein Isoforms / physiology
  • Rats
  • Rats, Sprague-Dawley
  • Reverse Transcriptase Polymerase Chain Reaction

Substances

  • Calcium Channels, L-Type
  • Calcium Channels, N-Type
  • DNA, Recombinant
  • L-type calcium channel alpha(1C)
  • Protein Isoforms
  • voltage-dependent calcium channel (P-Q type)