Abstract
The effects of calcium channel blocker, nifedipine on spinal monosynaptic reflexes were investigated in spinal cats. Nifedipine was administrated-locally (10, 50, 100s |imol/l) and intraperitoneally (5; 10, 20 mg/kg).
Adult cats (n=10), weighing 1,5-3 kg were anesthetized with ketamine (50 mg/kg, I.M.) and artificially ventilated. Animals were spinalized at C j level. A laminectomy was perfor¬med in the lumbosacral region. The ventral and dorsal roots of segment L5 were isolated and a pouch of skin was formed at the site of the dissection, to allow the exposed tissues to be covered with liquid paraffin, which was kept at 38.5±0.5°C with a heating pad. A po-lyethylene cannula was introduced into the left carotiid artery to moniter blood pressure, which was kept above 100 mmHg.
The dorsal root of segment L5 was placed on a silver-silver chloride wire electrode for sti-mulation throgh an isolatin unit. The reflex potentials were recorded from the ipsilateral L5 ventral root, mounted on a silver-silver chloride wire electrode.
Both systemic and local application of nifedipine produced a dose-dependent decrease in the amplitude of the monosynaptic reflexes (p< 0.05). Moreover, the latency of the mono-synaptic reflexes was increased after administration of the drug (p<0.005). These results show the presence of voltage-dependent calcium channels in the spinal cord and these channels may play an important role to regulate reflex respond.
Kalsiyum kanal blokerlerinden nifedipinin omurilik reflekslerine olan etkilerini araştırdık. Nifedipin 10, 50, 100 |im lokal ve 5, 10, 20 mg/kg peritonei olarak verildi. Yetişkin kediler (n=10), 1,5 - 3 kg ağırlığında, ketamin (50 mg/kg, i.m.) ile anestezi edildi ve suni ventilasyon uygulandı. Hayvanlar servikal seviyeden spinalize edildi. Havuz oluşturuldu, dokular likit vazelinle örtüldü ve sıcaklık 38.5±0.5°C'de muhafaza edildi. Karotis artere tansiyon aleti takıldı ve tansiyonun 100 mmHg'nın üzerinde olması sağlandı. Uyarı için L5 segmentin dorsal köküne gümüş-gümüş klorür tel elektrot yerleştirildi. Ref¬leks potansiyeller ipsilateral L5 ventral kökten kaydedildi, bu kayıtta da gümüş-gümüş klorür tel elektrot kullanıldı.
Nifedipinin hem sistemik hem de lokal dozları refleks cevabın amplitüdünü azalttı (p<0.05). Sistemik dozlar latenste uzama oluştururken (p<0.05), lokal dozlar latenste an¬lamlı değişiklik meydana getirmedi (p>0.05).
Bu sonuçlar bize omirilikte voltaja bağımlı kalsiyum kanallarının olabileceğini ve refleks cevabın düzenlenmesinde voltaja bağımlı kalsiyum kanallarının rol oynayabileceğini düşündürmektedir.
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| Primary Language | English |
|---|---|
| Journal Section | Basic Medical Sciences |
| Authors | |
| Publication Date | December 23, 2009 |
| Submission Date | December 13, 2009 |
| Published in Issue | Year 1996 Volume: 13 Issue: 1 |
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