Effects of computer controlled submaximal glucose utilization on myocardial energy potential and on survival time during acute strophantin intoxication in dogs.

We checked the effect of a 4 hourly computer controlled submaximal glucose utilization (CCSGU) of 12.01 +/- 1.19 mg/kg min under normoglycaemic conditions and of a simultaneous diminishing of myocardial NEFA supply on trigger mechanism of ventricular fibrillation during acute strophantin intoxication (4 micrograms/kg min) in 17 mongrel dogs. Dogs treated with CCSGU (protective group, n = 8) showed a nearly 30% (p less than 0.01) major survival time (47.6 +/- 3.6 min) before ventricular fibrillation occurred in comparison to a control group (33.1 +/- 3.7 min, n = 9). CCSGU induced a 90% higher left ventricular hydraulic work (5.18 +/- 0.57 Nm/g heart weight) during strophantin infusion compared to controls (2.75 +/- 0.47). No significant myocardial NEFA extraction was evident in the protective group. During CCSGU myocardial oxygen extraction was on a lower level in rest (15.8 +/- 1.0%, p less than 0.01) as well as during strophantin infusion (11.3 +/- 2.6%, p less than 0.01) compared to controls. In dogs treated with CCSGU nearly equal myocardial levels of HEP and lactate were found compared to controls in spite of a major survival time and higher left ventricular hydraulic work. A higher myocardial glycogen content was observed in the protective group (45.1 +/- 6.7 mumol/g w.w.) in comparison to controls (28.1 +/- 2.9, p less than 0.05). Our results prove that CCSGU using the device system GLUCON induces a shift in substrate utilization from NEFA to glucose, decreases myocardial oxygen extraction, increases myocardial glycogen content, enlarges heart work and protects against strophantin induced ventricular fibrillation.