Effects of Clonidine and Isoflurane on the Myocardial Contractility Behavior of Isolated Rat Hearts
DOI:
https://doi.org/10.1532/HSF98.20091136Abstract
Isoflurane is chosen as an anesthesia drug for cardiac surgeries, and its effectiveness and safety have been proved in countless clinical studies. Clonidine, a central ?-agonist, has recently been added to isoflurane to attenuate sympathetic hyperactivity by acting directly on its site of origin in the central nervous system. The ability of ?2-adrenoceptor agonists to inhibit central sympathetic outflow may benefit patients at risk of myocardial damage by improving myocardial oxygen demand and the supply ratio and contributing to hemodynamic stability. We investigated the effects of clonidine and isoflurane, alone and in combination, on the myocardial contractility of isolated rat hearts and found that use of clonidine plus isoflurane decreased the systolic pressure somewhat, but use of the drugs separately did not exhibit this effect. Clonidine plus isoflurane did not affect +(dP/dt)max, but it did decrease -(dP/dt)max significantly compared with the use of isoflurane alone. These results indicate that clonidine and isoflurane have the capacity to interact with each other. The capacity of clonidine to decrease isoflurane's inotropic effect could theoretically contribute to improving the myocardial oxygen demand and the supply ratio, decreasing surgical stress, and benefiting patients at risk of myocardial damage.References
Agnew NM, Pennefather SH, Russell GN. 2002. Isoflurane and coronary heart disease. Anaesthesia 57:338-47.nCoetzee A, Skein W, Grenade S, Lochner A. 1993. Enflurane and isoflurane reduce reperfusion dysfunction in the isolated rat heart. Anesth Analg 76:602-8.nCrystal GJ, Zhou X, Gurevicius J, et al. 2000. Direct coronary vasomotor effects of sevoflurane and desflurane in in situ canine hearts. Anesthesiology 92:1103-13.nDupin JB. 2008. The role of alpha adrenergic agonists in the myocardial ischemia prevention. Cardiovasc Sci Forum 3:5-7.nDupin JB, Mercante JGB, Gomes OM. 2001. New flexible catheterballon for isolated heart study. Latin Am Arch Cardiovasc Sci 2:37-42.nGomes OM, Gomes ES, Neves HJ, et al. 1997. Modificação da técnica de Langendorff para estudo de coração isolado com utilização de sistema descartável [abstract]. Paper presented at: VIII Congresso da Sociedade Mineira de Cardiologia; July 3-5, 1997; Belo Horizonte, Brazil.n[ILAR] Institute of Laboratory Animal Research, Commission on Life Sciences, National Research Council. 1996. Guide for the Care and Use of Laboratory Animals. Washington, DC: National Academies Press.nKobinger W. 1978. Central alpha-adrenergic systems as targets for hypotensive drugs. Rev Physiol Biochem Pharmacol 81:39-100.nMaurer W, Hausen M, Krämer B, Kübler W. 1983. Effect of centrally acting agent clonidine on circulating catecholamines at rest and during exercise: comparison with the effects of beta-blocking agents. Chest 83:366-9.nReid IA, Ahn JN, Trinh T, Schackelford R, Weintraub M, Keil LC. 1984. Mechanism of suppression of vasopressin and adrenocorticotropic hormone secretion by clonidine in anesthetized dogs. J Pharmacol Exp Ther 229:1-8.nRivenes SM, Lewin MB, Stayer SA, et al. 2001. Cardiovascular effects of sevoflurane, isoflurane, halothane, and fentanyl-midazolam in children with congenital heart disease: an echocardiographic study of myocardial contractility and hemodynamics. Anesthesiology 94:223-9.nStühmeier KD, Mainzer B, Cierpka J, Sandmann W, Tarnow J. 1996. Small, oral dose of clonidine reduces the incidence of intraoperative myocardial ischemia in patients having vascular surgery. Anesthesiology 85:706-12.nYin YC, Chow LH, Tsao CM, et al. 2002. Oral clonidine reduces myocardial ischemia in patients with coronary artery disease undergoing noncardiac surgery. Acta Anaesthesiol Sin 40:197-203.n
