Pharmacological profile of store-operated channels in cerebral arteriolar smooth muscle cells.
1. In this study, we determined a pharmacological profile of store-operated channels (SOCs) in smooth muscle cells of rabbit pial arterioles. Ca(2+)-indicator dyes, fura-PE3 or fluo-4, were used to track [Ca(2+)](i) and 10 micro M methoxyverapamil (D600) was present in all experiments on SOCs to prevent voltage-dependent Ca(2+) entry. Store depletion was induced using thapsigargin or cyclopiazonic acid. 2. SOC-mediated Ca(2+) entry was inhibited concentration dependently by Gd(3+) (IC(50) 101 nM). It was also inhibited by 10 micro M La(3+) (70% inhibition, N=5), 100 micro M Ni(2+) (57% inhibition, N=5), 75 micro M 2-aminoethoxydiphenylborate (66% inhibition, N=4), 100 micro M capsaicin (12% inhibition, N=3) or preincubation with 10 micro M wortmannin (76% inhibition, N=4). It was completely resistant to 1 micro M nifedipine (N=5), 10 micro M SKF96365 (N=6), 10 micro M LOE908 (N=14), 10-100 micro M ruthenium red (N=1+2), 100 micro M sulindac (N=4), 0.5 mM streptomycin (N=3) or 1 : 10,000 dilution Grammostolla spatulata venom (N=4). 3. RT-PCR experiments on isolated arteriolar fragments showed expression of mRNA species for TRPC1, 3, 4, 5 and 6. 4. The pharmacological profile of SOC-mediated Ca(2+) entry in arterioles supports the hypothesis that these SOCs are distinct from tonically active background channels and several store-operated and other nonselective cation channels described in other cells. Similarities with the pharmacology of TRPC1 support the hypothesis that TRPC1 is a subunit of the arteriolar smooth muscle SOC.
Flemming
R
R
School of Biomedical Sciences, University of Leeds, Leeds, LS2 9JT.
Xu
S Z
SZ
Beech
D J
DJ
D000730:Androstadienes / Q000737:chemistry / Q000494:pharmacology; D000818:Animals; D001160:Arterioles / Q000187:drug effects / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism*; D002536:Cerebral Arteries / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000737:chemistry / Q000494:pharmacology; D011817:Rabbits; D000077191:Wortmannin
D000730:Androstadienes; D015220:Calcium Channels; D009543:Nifedipine; D002118:Calcium; D000077191:Wortmannin