[Inhibition of nitric oxide synthesis during bacterial shock does not prevent development of resistant hypotension...

The study subject was the white rat-males Wistar after intra-peritoneal injection of the mixture of St. aureus and B. pyocyaneus daily cultures in the dose calculated as 1 milliard microbial organisms of each species per 100 g b.w., as well as the vascular preparations isolated from aortas of those rats. The aim is to study nitric oxide role in the development of resistant hypotension under generalization of the purulent infection. Infection of the animals with a mixture of gram-positive and gram-negative cultures led to the development of the pathological process, which can be considered as a septic (bacterial) shock. A primary lowering of the vascular tone caused by depression of the myocardial pump and contractile functions was observed. Injection of methylene blue or NOS blockers (L-NAME, S-methyl-thiourea) to the infected animals in the moment of hypotension development caused only a short-term rise in blood pressure. Survival rate in such animals was significantly lower compared to the control infected animals. Repeated injections of those agents hastened death of the experimental animals. The experiments in vitro revealed no dilatory effect of acetylcholine with preserved sensitivity of the vascular preparations to adrenomimetics and exogenous nitric oxide in both control infected animals and animals injected with methylene blue or NOS blockers. The data obtained suggested that resistant hypertension in terminal stages of septic shock is nitric oxide-independent.