No Impairment of Sympathetic Neurotransmission in Stunned Myocardium

Schulz, Rainer; Frehen, D.; Heusch, Gerd

doi:10.1007/978-3-662-11038-6_22

Cited by 1 publication

(2 citation statements)

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“…First, the baseline hemodynamics in the open-chest anesthetized state in this study were similar to basal parameters in telemetrically monitored animals in our laboratory (heart rate, ϳ97 Ϯ 14 beats/ min; systolic pressure, ϳ108 Ϯ 12 mmHg). Second, the magnitude of improvement in both regional and global function during stellate stimulation is similar to those observed by other investigators (14,39). Finally, the anesthetic regimen used in this study was specifically chosen to minimize potential effects on sympathetic tone, with continuous infusions of low to moderate doses of propofol and ketamine.…”

Section: Discussionmentioning

confidence: 78%

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

Ovchinnikov

Suzuki

Canty

et al. 2005

American Journal of Physiology-Heart and Circulatory Physiology

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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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Section: Discussionmentioning

confidence: 78%

“…Schulz et al (39) have concluded that there are no alterations in sympathetic nerve dysfunction in stunned myocardium. After completely reversible ischemia of 15-min duration in dogs, they noted that there was parallel recovery of resting wall thickening and function during stellate stimulation and norepinephrine infusion.…”

Section: Discussionmentioning

confidence: 98%