ABSTRACT
Abstract Objective: The aim of this study was to compare the efficacy of two different papaverine concentrations (0.5 mg/ml and 2 mg/ml) for vasospasm prevention and their impact on endothelium integrity. Methods: We have studied distal segments of radial arteries obtained by no-touch technique from coronary artery bypass graft (CABG) patients (n=10). The vasodilatory effect of papaverine (concentrations of 0.5 mg/ml and 2 mg/ml) was assessed in vitro, in isometric tension studies using ex vivo myography (organ bath technique) and arterial rings precontracted with potassium chloride (KCl) and phenylephrine. The impact of papaverine on endothelial integrity was studied by measurement of the percentage of vessel's circumference revealing CD34 endothelial marker. Results: 2 mg/ml papaverine concentration showed stronger vasodilatatory effect than 0.5 mg/ml, but it caused significantly higher endothelial damage. Response to KCl was 7.35±3.33 mN for vessels protected with papaverine 0.5 mg/ml and 2.66±1.96 mN when papaverine in concentration of 2 mg/ml was used. The histological examination revealed a significant difference in the presence of undamaged endothelium between vessels incubated in papaverine 0.5 mg/ml (72.86±9.3%) and 2 mg/ml (50.23±13.42%), P=0.002. Conclusion: Papaverine 2 mg/ml caused the higher endothelial damage. Concentration of 0.5 mg/ml caused better preservation of the endothelial lining.
Subject(s)
Humans , Male , Female , Aged , Papaverine/administration & dosage , Vasodilator Agents/administration & dosage , Coronary Artery Disease/surgery , Endothelium, Vascular/drug effects , Radial Artery/drug effects , Coronary Vasospasm/prevention & control , Papaverine/adverse effects , Papaverine/pharmacology , Vasoconstriction/drug effects , Vasodilation/drug effects , Vasodilator Agents/adverse effects , Vasodilator Agents/pharmacology , Coronary Artery Disease/physiopathology , Coronary Artery Bypass/methodsABSTRACT
Background: Endothelial dysfunction is associated to a lower production of nitric oxide and a reduction of endothelium mediated vasodilation. Aim: To study the effects of pharmacological agents that modify nitric oxide synthetase (NOS) activity on tension changes induced by phenylephrine in rings of internal mammary and radial arteries and saphenous vein. Material and methods: Vessel rings of 7 to 10 mm length were obtained from 32 patients subjected to coronary vascular surgery Fourteen samples of radial artery, 12 samples of internal mammary artery and 15 samples of saphenous vein were obtained. A maximal contraction was induced with KC1 and dose response curves for phenylephrine (FE) in the absence or presence of L-arginine and L-arginine methyl ester (L-NAME), were constructed. Results: The tension induced by FE in internal mammary artery and saphenous vein reached a maximum, near 90 percent of 80 mM KCl-induced contraction, but in the radial artery, it reached a maximum of 63 percent (p <0.05). In all vessels, the dose response curves were significantly shifted to the right by L-arginine and to the íeft by L-NAME. Conclusions: Pre-incubation of human rings with L-ARG or L-NAME, changed the response to FE induced contraction, which may be related to different degrees of endothelial nitric oxide production or NO sensitivity. The basal NO production in radial artery seems to be larger than the other vessels.
Subject(s)
Humans , Arginine/pharmacology , Enzyme Inhibitors/pharmacology , Muscle, Smooth, Vascular/drug effects , NG-Nitroarginine Methyl Ester/pharmacology , Nitric Oxide Synthase/antagonists & inhibitors , Phenylephrine/pharmacology , Vasoconstrictor Agents/pharmacology , Endothelium, Vascular/drug effects , Endothelium, Vascular/enzymology , Mammary Arteries/drug effects , Muscle, Smooth, Vascular/enzymology , Radial Artery/drug effects , Saphenous Vein/drug effects , VasoconstrictionABSTRACT
Este trabajo se diseñó para evaluar la efectividad de diversos vasodilatadores aplicados tópicamente para prevenir la hiperreactividad de las arterias radiales (AR) implantadas como bypass aortocoronario. De cada uno de los remanentes de AR provenientes de 20 pacientes operados se obtuvieron 4 anillos que se incubaron por 30 minutos en condiciones control (n = 20) o en presencia de 30 µM de diltiazem (DILT, n = 6), mibefradil (MIBE, n = 4) o mezcla de verapamil + nitroglicerina (VP-NTG, n = 6). La subsiguiente exposición a CIK 80 mM (en ausencia de vasodilatadores) provocó una contracción sostenida en los anillos control, que fue atenuada en un 35 ñ 9 por ciento por DILT, 48 ñ 13 por ciento por VP-NTG y 69 ñ 20 por ciento por MIBE (p < 0.05). La preincubación con vasodilatadores provocó también la disminución de frecuencia e intensidad de contracciones rítmicas espontáneas de la AR. En anillos almacenados en frío por 24 hs y luego reestimulados con CIK 80 mM el efecto depresor fue aun evidente: DILT 53 ñ 6 por ciento, VP-NTG 46 ñ 14 por ciento y MIBE 61 ñ 9 por ciento (p < 0.05). El efecto del MIBE fue más intenso y persistente que el de DILT o VP-NTG, aún a concentraciones que provocan un igual efecto depresor inicial. Se concluye que la exposición a vasodilatadores durante un período equivalente a la duración de la preparación de la AR a implantar produce una atenuación de la reactividad arterial que proporcionaría una protección adicional contra el espasmo durante el postoperatorio inmediato.