The role of P-type calcium channels in the depolarization-induced activation of nitric oxide synthase in frontal cortex.
In this study we demonstrate that 50 mM K+ stimulates the conversion of L-[3H]arginine to L-[3H]citrulline and that this effect is blocked by 10 microM N omega-nitro-L-arginine, a nitric oxide synthase inhibitor, and Ca(2+)-free conditions. Amiloride (1 mM) and low Na+ conditions were used to test the possible involvement of the Na(+)-Ca2+ exchanger. These treatments were without effect. The calcium channel blockers 10 mM Mg2+, 100 microM Cd2+, and 10 mM Co2+ also blocked the K+ response, suggesting the involvement of voltage-dependent calcium channels (VDCCs). The specific VDCC involved seems to be the P type, as funnel-web spider toxin blocked the response whereas 200 microM Ni2+, 10 microM nifedipine, and 100 nM omega-conotoxin did not.
Alagarsamy
S
S
Department of Pharmacology and Toxicology, University of Texas Medical Branch, Galveston 77555-1031.
Lonart
G
G
Johnson
K M
KM
D000584:Amiloride / Q000494:pharmacology*; D000594:Amino Acid Oxidoreductases / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002352:Carrier Proteins / Q000378:metabolism; D002956:Citrulline / Q000378:metabolism; D004789:Enzyme Activation; D005625:Frontal Lobe / Q000201:enzymology* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D016202:N-Methylaspartate / Q000037:antagonists & inhibitors; D019001:Nitric Oxide Synthase; D019335:Nitroarginine; D010455:Peptides / Q000494:pharmacology; D010875:Pipecolic Acids / Q000494:pharmacology; D011073:Polyamines / Q000494:pharmacology; D011188:Potassium / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D019831:Sodium-Calcium Exchanger; D020960:omega-Conotoxins
D002121:Calcium Channel Blockers; D015220:Calcium Channels; D002352:Carrier Proteins; C071920:FTX, spider toxin; D010455:Peptides; D010875:Pipecolic Acids; D011073:Polyamines; D019831:Sodium-Calcium Exchanger; D020960:omega-Conotoxins; C053423:Conus magus toxin; D019335:Nitroarginine; D002956:Citrulline; C053672:selfotel; D016202:N-Methylaspartate; D000584:Amiloride; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D011188:Potassium