Vasodilating prostaglandin E does not reproduce interleukin-1β-induced oxygen metabolism abnormalities in rabbits.

BACKGROUND

We have reported that administration of recombinant human interleukin (IL)-1β induced circulatory shock in rabbits by causing overproduction of vasodilating prostaglandin(s) and simultaneously impaired oxygen metabolism by causing an abnormal dependence of oxygen consumption (VO) on oxygen delivery (DO). The present study was carried out to compare the effect of administration of exogenous PGE with that of IL-1β on oxygen metabolism.

METHODS

Sixteen rabbits were assigned to one of three groups and given a single injection of 10 μg/kg IL-1β (IL-1β group,  = 5), continuous infusion of 1 μg/kg/min PGE (PGE group,  = 6), or saline (control group,  = 5). All rabbits were subjected to stepwise cardiac tamponade to decrease DO by inflating a balloon placed into the pericardial sac. The VO/DO relation was analyzed by the dual-line method.

RESULTS

Both IL-1β and PGE decreased the baseline value of mean arterial pressure by approximately 25% without inducing significant alteration of the cardiac index. With respect to the VO/DO relation, the slope of the supply-independent line was significantly increased in the IL-1β group (y = 0.13x + 6.4), but not in the PGE group (y = 0.01x + 10.0) compared to that in the control group (y = 0.05x + 8.7).

CONCLUSION

These results indicate that simple vasodilation and hypotension induced by administration of PGE are insufficient to account for the abnormal oxygen metabolism induced by IL-1β.