Preferential inhibition by a novel Na(+)/Ca(2+) channel blocker NS-7 of severe to mild hypoxic injury in rat cerebrocortical slices: A possible involvement of a highly voltage-dependent blockade of Ca(2+) channel.
The hypoxic injury was induced in rat cerebrocortical slices by the exposure to hypoxia for 45 min in the absence or presence of 3 mM glucose, followed by reoxygenation for 5 h. The injury was more pronounced in the absence of glucose (severe hypoxic injury) than in the presence of glucose (mild hypoxic injury). A novel Na(+)/Ca(2+) channel blocker, NS-7 [4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy) pyrimidine hydrochloride], at 3 to 30 microM inhibited preferentially the severe hypoxic injury, whereas MK-801, omega-conotoxin GVIA (omega-CTX), and N(G)-nitro-L-arginine methylester suppressed preferentially the mild hypoxic injury. The extracellular cyclic GMP formation, a marker of nitric oxide synthesis, was enhanced during hypoxia, although the extent was greater in the absence of glucose. As observed in the hypoxic injury, NS-7 preferentially inhibited the cyclic GMP formation induced by severe hypoxic insults, whereas MK-801 or omega-CTX reduced it under mild hypoxic condition. When 30 to 50 mM KCl was applied to normoxic slices, a concentration-dependent increase in the extracellular cyclic GMP formation was observed. NS-7 blocked the cyclic GMP formation induced by 50 mM KCl but not by 30 to 40 mM KCl, whereas omega-CTX suppressed only the 30 mM KCl-evoked response. In primary neuronal culture, NS-7 reversed KCl-induced increase in intracellular Ca(2+) in which the inhibition was marked when the KCl concentration was increased. These findings suggest that NS-7, unlike other neuroprotective compounds used in this study, is more effective in severe hypoxic injury. The highly voltage-dependent Ca(2+) channel blockade may contribute to the mode of neuroprotective action of NS-7.
Oka
M
M
Research Laboratories, Nippon Shinyaku Co., Ltd., Nishiohji Hachijo Minami-ku, Kyoto, Japan. m.oka@po.nippon-shinyaku-co.jp
Itoh
Y
Y
Ukai
Y
Y
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002118:Calcium / Q000378:metabolism; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000187:drug effects / Q000473:pathology*; D004594:Electrophysiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D005110:Extracellular Space / Q000187:drug effects / Q000378:metabolism; D006157:Guanosine Monophosphate / Q000096:biosynthesis; D002534:Hypoxia, Brain / Q000473:pathology*; D066298:In Vitro Techniques; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D018696:Neuroprotective Agents / Q000494:pharmacology*; D009543:Nifedipine / Q000494:pharmacology; D009569:Nitric Oxide / Q000096:biosynthesis; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D052248:Nitric Oxide Synthase Type I; D011743:Pyrimidines / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers
C106144:4-(4-fluorophenyl)-2-methyl-6-(5-piperidinopentyloxy)pyrimidine hydrochloride; D002121:Calcium Channel Blockers; D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D018696:Neuroprotective Agents; D011743:Pyrimidines; D026941:Sodium Channel Blockers; D009569:Nitric Oxide; D006157:Guanosine Monophosphate; D000255:Adenosine Triphosphate; D019001:Nitric Oxide Synthase; D052248:Nitric Oxide Synthase Type I; C496322:Nos1 protein, rat; D009543:Nifedipine; D002118:Calcium