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Ovchinnikov V, Suzuki G, Canty JM, et al. Blunted functional responses to pre- and postjunctional sympathetic stimulation in hibernating myocardium. Am J Physiol Heart Circ Physiol. 2005;289(4):H1719-28doi: 10.1152/ajpheart.00273.2005.
Ovchinnikov, V., Suzuki, G., Canty, J. M., & Fallavollita, J. A. (2005). Blunted functional responses to pre- and postjunctional sympathetic stimulation in hibernating myocardium. American journal of physiology. Heart and circulatory physiology, 289(4), H1719-28. https://doi.org/10.1152/ajpheart.00273.2005
Ovchinnikov, Vladislav, et al. "Blunted functional responses to pre- and postjunctional sympathetic stimulation in hibernating myocardium." American journal of physiology. Heart and circulatory physiology vol. 289,4 (2005): H1719-28. doi: https://doi.org/10.1152/ajpheart.00273.2005
Ovchinnikov V, Suzuki G, Canty JM, Fallavollita JA. Blunted functional responses to pre- and postjunctional sympathetic stimulation in hibernating myocardium. Am J Physiol Heart Circ Physiol. 2005 Oct;289(4):H1719-28. doi: 10.1152/ajpheart.00273.2005. Epub 2005 May 27. PMID: 15923318.
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Am J Physiol Heart Circ Physiol. 2005 Oct;289(4):H1719-28. doi: 10.1152/ajpheart.00273.2005. Epub 2005 May 27.

Blunted functional responses to pre- and postjunctional sympathetic stimulation in hibernating myocardium.

American journal of physiology. Heart and circulatory physiology

Vladislav Ovchinnikov, Gen Suzuki, John M Canty, James A Fallavollita

Affiliations

  1. Center for Research in Cardiovascular Medicine, University at Buffalo, Buffalo, New York 14214, USA.

PMID: 15923318 DOI: 10.1152/ajpheart.00273.2005

Abstract

Regional reductions in norepinephrine-tracer uptake are found in pigs with hibernating myocardium. Clinical studies would suggest that this is evidence for denervation; however, the functional responses to sympathetic stimulation have not been evaluated, and our previous studies with beta-adrenergic stimulation have not suggested denervation hypersensitivity. Therefore, pigs were chronically instrumented to produce hibernating myocardium characterized by chronic regional dysfunction and histological viability. Open-chest studies were performed to determine changes in regional function in response to both pre- and postjunctional stimulation. Regional segment shortening was reduced at rest in hibernating myocardium compared with controls (13 +/- 3% vs. 27 +/- 3%, P = 0.004). During stellate ganglion stimulation, regional function increased in both groups of animals (P = 0.008 vs. baseline), but the increase in hibernating myocardium was blunted compared with controls (Delta%, 3 +/- 2% vs. 8 +/- 3%, P = 0.04). Similar results occurred with intracoronary tyramine (10 mug/kg). Functional improvement during intravenous epinephrine infusion (0.35 mug.kg(-1).min(-1)) was also blunted in hibernating myocardium compared with controls (Delta%, 7 +/- 1% vs. 15 +/- 2%, P = 0.04). Even when the improvement in function was expressed relative to the reduced baseline, there was no evidence for catecholamine-mediated hypersensitivity in hibernating myocardium. We therefore conclude that functional responses to both pre- and postjunctional sympathetic stimulation are blunted in pigs with hibernating myocardium. In contrast to previous studies of infarcted, denervated, and acutely stunned myocardium, there is no catecholamine-induced hypersensitivity in hibernating myocardium. These data suggest a downregulation in functional responses to stimulation that would protect hibernating myocardium from demand-induced ischemia at the expense of contractile reserve during sympathetic stimulation.

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