RESUMEN
1. The effects of chronic lithium administration on the relaxant responses of rat thoracic aortic rings in the presence of indomethacin (a cyclo-oxygenase inhibitor) and/or NG-nitro-L-arginine (L-NOARG; a nitric oxide synthase inhibitor) to acetylcholine (ACh) or sodium nitroprusside were investigated in the present study. 2. Acetylcholine produced a concentration-dependent relaxation in vessels precontracted by phenylephrine (PE), while in lithium-treated rats the maximal relaxation was significantly increased. 3. Indomethacin (20 mumol/L) significantly potentiated the ACh-induced relaxation in lithium-treated and control rats. 4. NG-Nitro-L-arginine (1 mumol/L) decreased the ACh-induced relaxation in both control and lithium-treated rats. In contrast, indomethacin (20 mumol/L) reversed the inhibitory effect of L-NOARG. 5. Sodium nitroprusside produced similar concentration-dependent relaxations of vessels from both control and lithium-treated rats, which was not affected by indomethacin. In endothelium-denuded rings, indomethacin (20 mumol/L) caused a rightward shift in the concentration-contraction curve to PE. 6. These data support evidence for a possible increase in endothelium-dependent relaxation induced by ACh during long-term administration of lithium in rat aortic rings.
Asunto(s)
Antimaníacos/farmacología , Endotelio Vascular/efectos de los fármacos , Cloruro de Litio/farmacología , Vasodilatación/efectos de los fármacos , Acetilcolina/farmacología , Animales , Antiinflamatorios no Esteroideos/farmacología , Aorta/efectos de los fármacos , Aorta/fisiología , Endotelio Vascular/fisiología , Inhibidores Enzimáticos/farmacología , Indometacina/farmacología , Masculino , Nitroarginina/farmacología , Ratas , Ratas Sprague-Dawley , Vasodilatación/fisiología , Vasodilatadores/farmacologíaRESUMEN
1. Neuromuscular blocking effect of gentamicin and neomycin evaluated in phrenic-nerve hemidiaphragm preparation in normal and diabetic rats and IC50 of both drugs determined from LDR curves. 2. IC50 of gentamicin was 0.91 +/- 0.05 and 1.67 +/- 0.08 mmol.l-1 for normal and diabetic rats respectively. 3. IC50 of neomycin was 0.42 +/- 0.02 and 0.61 +/- 0.06 mmol.l-1 for normal and diabetic rats respectively. 4. The results show diabetic rats are more resistant to neuromuscular blocking action of aminoglycoside antibiotics (AGs). 5. Replacement of sodium by lithium (1.5 and 5 mmol.l-1) in the media, reduced this effect of aminoglycosides (AGs) significantly. 6. It appears that the prevention of AGs induced-neuromuscular blockade by lithium is not significantly different in both groups.
