Abstract
BackgroundRadial artery (RA) is widely used in coronary artery bypass (CABG) surgery and the prevention of spasm is crucial for graft patency. Botulinum toxin A (BTX-A) and B are commonly used for aesthetic reasons and neuromuscular disorders. They are proven to raise blood flow and increase survival of ischemic skin flaps. In this study we evaluated and compared the vasodilator effects of BTX-A and papaverine on human RA grafts.MethodsAfter resting 60 min in isolated organ baths, human RA grafts were examined. Contraction responses for different doses of serotonin (5-HT) and endothelin-1 (ET-1) were evaluated as a percent of maximum contraction response elicited by 80 mM potassium chloride (KCl). The inhibitory effects of BTX-A and papaverine on contraction responses taken at the 0th hour were compared with the 1st and 2nd hour responses. Inhibitory effects of BTX-A and papaverine against the contractile agent were evaluated by comparing the results of the first and last (0th and 2nd hour) application.ResultsIn low concentrations, when we compared the effects of BTX-A (10− 8 M) and papaverine (10− 6 M) on 5-HT, papaverine was found to be more effective at both the 0th and 2nd hour (p < 0.05). Both BTX-A and papaverine inhibited the maximum contractile effect of ET-1 to the same extent at the 0th hour; but, the inhibitory effect of BTX-A was significantly stronger at the 2nd hour (p < 0.05).In high concentrations, when we compared the effects of BTX-A (10− 6 M) and papaverine (10− 4 M) on 5-HT, papaverine showed stronger inhibition (p < 0.05), whereas both agents had similar action of inhibition on ET-1 mediated maximum contraction responses.ConclusionBTX-A inhibits both ET-1 and 5-HT induced contractions and its effectiveness does not decrease over time as observed with papaverine. This study is the first in the literature using human RA for prevention of vasospasm by BTX-A.
Highlights
Radial artery (RA) is widely used in coronary artery bypass (CABG) surgery and the prevention of spasm is crucial for graft patency
The contraction of RA is a major problem and Botulinum toxin (BTX)-A appears to be a good agent for resolving this problem. We examined both vasodilator effects of Botulinum toxin A (BTX-A) and papaverine on human RA grafts in conjunction with possible histopathological changes, with a great potential of use in our routine daily practice
The effects of BTX-A over the contraction responses of 5HT and ET-1 contraction responses obtained by 5-HT In tissues incubated with 10− 8 M BTX-A (n = 6), significant inhibition was detected in contraction responses obtained by high doses of 5-HT concentrations (10− 7–10− 6 M) (p < 0.05)
Summary
Radial artery (RA) is widely used in coronary artery bypass (CABG) surgery and the prevention of spasm is crucial for graft patency. Botulinum toxin A (BTX-A) and B are commonly used for aesthetic reasons and neuromuscular disorders. They are proven to raise blood flow and increase survival of ischemic skin flaps. In this study we evaluated and compared the vasodilator effects of BTX-A and papaverine on human RA grafts. The success of the surgery depends on the patency of the conduits used for bypassing the occluded coronary arteries. In the operating room papaverine (1 mg/ mL, 2.7 mmol/L) is satisfactory for topical use. Sodium nitroprusside (1.7 mmol/L, 0.5 mg/mL), used topically, is very potent and may cause hypotension if it enters the systemic circulation [2]
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