Ann Thorac Surg 2006;82:1572-1573
© 2006 The Society of Thoracic Surgeons
Correspondence
Resveratrol or Higher Arterial Blood Pressure Protects the Spinal Cord From Ischemia-Reperfusion Injury?
Ioannis K. Toumpoulis, MD
Department of Cardiothoracic Surgery, Attikon Hospital Center, Georgiou Sisini 31, Athens, 11528 Greece
(Email: toumpoul{at}otenet.gr).
To the Editor:
I read with interest the article titled "Resveratrol, A Natural Red Wine Polyphenol, Reduces Ischemia-Reperfusion-Induced Spinal Cord Injury" [1]. I congratulate Kaplan and colleagues [1] on their study of resveratrol use to provide ischemic spinal cord protection. In this study the authors evaluated the effect of resveratrol (100 µg/kg) on the spinal cord in a rabbit experimental model of 30-minute infrarenal aortic cross clamping. They used 16 rabbits assigned either to a treated group (n = 8, resveratrol was infused 15 minutes before aortic occlusion) or a control group (n = 8, untreated group). All animals were sacrificed at 24 hours and groups were compared clinically using the Tarlov score, while histopathologic assessment and measurements of malondiadehyde levels and myeloperoxidase activity were performed. Neurologic impairment, reduction of the number of motor neurons, malondiadehyde levels and myeloperoxidase activity were significantly lower in the resveratrol group.
In a previous published study, Kiziltepe and colleagues [2] used almost the same experimental rabbit model and evaluated the effect of resveratrol on the spinal cord using two different doses (1 mg/kg and 10 mg/kg of resveratrol, which were administered 30 minutes before infrarenal aortic occlusion). The protected effect of resveratrol in this study was not prominent in animals that received 1 mg/kg, and only animals that received 10 mg/kg resveratrol experienced spinal cord protection.
In our recently published studies [3, 4], we have demonstrated that immediate ischemic preconditioning without hypotension prevents spinal cord injury in a porcine model of descending thoracic aortic occlusion. In our studies it was very important to maintain the arterial systolic blood pressure > 100 mm Hg during the reperfusion interval, while we have underscored that hypotensive animals (80 to 90 mm Hg arterial systolic blood pressure) during the reperfusion interval became paraplegic at 48 hours postoperatively.
Kaplan and colleagues [1] observed significantly increased proximal aortic blood pressure in the resveratrol group as well as distal aortic blood pressure during cross clamping. This phenomenon itself may explain the protective effect on the spinal cord in this group. How did the authors explain the previously mentioned increased arterial blood pressures and what would have been the results if the two groups had similar arterial blood pressures? A possible reply could be extracted from the study of Kiziltepe and colleagues [2] in which they used a 10 times higher dose (1 mg/kg instead of 100 µg/kg in the study of Kaplan and colleagues [1]) and there was no elevation in arterial blood pressure during the reperfusion interval in the resveratrol group, and there was no difference found when compared with the controls.
Kaplan and colleagues [1] claimed in the Comment section of their article that a detailed Medline research regarding resveratrol was performed to determine the dose of resveratrol. The study of Kiziltepe and colleagues [2] (published in 2004) is not referenced by Kaplan and colleagues [1]. Were the authors aware of this study and the used doses of resveratrol? Finally, why did the authors choose to follow-up the animals for only 24 hours postoperatively? It is well-known that among such studies an appropriate time interval for follow-up should be 5 or 7 days postoperatively to exclude any transient protection or the effect of delayed paraplegia [3–5].
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References
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- Kaplan S, Bisleri G, Morgan JA, Cheema FH, Oz MC. Resveratrol, a natural red wine polyphenol, reduces ischemia-reperfusion-induced spinal cord injury Ann Thorac Surg 2005;80:2242-2249.[Abstract/Free Full Text]
- Kiziltepe U, Turan NN, Han U, Ulus AT, Akar F. Resveratrol, a red wine polyphenol, protects spinal cord from ischemia-reperfusion injury J Vasc Surg 2004;40:138-145.[Medline]
- Toumpoulis IK, Anagnostopoulos CE, Drossos GE, Malamou-Mitsi VD, Pappa LS, Katritsis DG. Early ischemic preconditioning without hypotension prevents spinal cord injury caused by descending thoracic aortic occlusion J Thorac Cardiovasc Surg 2003;125:1030-1036.[Abstract/Free Full Text]
- Toumpoulis IK, Papakostas JC, Matsagas MI, et al. Superiority of early relative to late ischemic preconditioning in spinal cord protection after descending thoracic aortic occlusion J Thorac Cardiovasc Surg 2004;128:724-730.[Abstract/Free Full Text]
- Kakimoto M, Kawaguchi M, Sakamoto T, et al. Evaluation of rapid ischemic preconditioning in a rabbit model of spinal cord ischemia Anesthesiology 2003;99:1112-1117.[Medline]
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