Coexpression of voltage-dependent calcium channels Cav1.2, 2.1a, and 2.1b in vascular myocytes.
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.
Andreasen
Ditte
D
Physiology and Pharmacology, University of Southern Denmark, Odense, Denmark.
Friis
Ulla G
UG
Uhrenholt
Torben R
TR
Jensen
Boye L
BL
Skøtt
Ole
O
Hansen
Pernille B
PB
D000818:Animals; D001011:Aorta / Q000166:cytology / Q000378:metabolism; D020746:Calcium Channels, L-Type / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D020864:Calcium Channels, N-Type / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D002460:Cell Line; D004274:DNA, Recombinant; D005455:Fluorescent Antibody Technique; D014644:Genetic Variation; D007668:Kidney / Q000098:blood supply; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D032389:Myocytes, Smooth Muscle / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction
D020746:Calcium Channels, L-Type; D020864:Calcium Channels, N-Type; D004274:DNA, Recombinant; D020033:Protein Isoforms; C419385:L-type calcium channel alpha(1C)