To evaluate the effects of hyperbaric oxygen (HBO) therapy on zymosan-induced shock in rats. Zymosan, a cell wall component of the yeast Saccharomyces cerevisiae, induces inflammation by causing the ...production of various cytokines and pro-inflammatory mediators. The administration of zymosan to rats represents a new experimental shock model by inducing acute peritonitis, severe hypotension, and signs of systemic illness. However, it has been recently proposed that the zymosan-induced shock, like septic shock, may be mediated by overproduction of nitric oxide.
Experimental study.
Institute of Pharmacology and Toxicology, 2nd University of Naples, Naples, Italy.
Male rats were treated with zymosan (500 mg/kg) by intraperitoneal route, with HBO (2 Absolute Atmosphere) or with zymosan and HBO (2 Absolute Atmosphere).
Peritoneal exudate, plasma, and peritoneal nitric oxide metabolites (NOx) and zymosan determined a time-dependent increase in peritoneal and plasma NOx concentrations, and peritoneal leukocytes were determined. Moreover, symptomatology was observed. The administration of zymosan caused the appearance of a severe illness in the rats characterized by ruffled fur, lethargy, conjunctivitis, diarrhea, and a significant loss of body weight. All zymosan-treated rats developed an acute peritonitis, producing turbid exudate. Zymosan determined a time-dependent increase in peritoneal, plasma NOx, and tumor necrosis factor (TNF)-alpha concentrations. Morbidity of zymosan shocked rats has been attenuated and no mortality was observed by treatment with HBO. These findings were associated with a significant reduction either of peritoneal leukocytes and exudate, or plasma and peritoneal NOx concentrations. Moreover, TNF-alpha levels were significantly reduced in animals shocked by zymosan and treated with HBO.
The cardiovascular and respiratory effects of dermorphin (D) have been evaluated in freely moving or anesthetized normotensive and spontaneously hypertensive male rats. Intravenously or ...intracerebroventricularly administration of D produced arterial hypotension with sinus bradycardia and respiratory depression. Naloxone antagonized the effects of D. Atrial natriuretic antipeptide IgG reduced the cardiovascular responses without any significant modification of respiratory response. ICI 174864, naloxonazine and binaltorphimine did not reduce the cardiovascular and respiratory effects. In hypertensive rats D produced more intense and longer cardiovascular effects than those seen in normotensive animals. D effects involve the activation of mu and k opioid receptors for cardiovascular responses and mu 2 opioid receptors for respiratory depression without any significant effect on delta receptors. The release of atrial natriuretic peptide also appears to be involved in the cardiovascular effects of D.
As part of an investigation of the quality of the return to consciousness after anaesthesia, a comparison was made between recovery times in 60 patients divided into three groups, subjected to ...general anaesthesia and shallow maintenance with halothane, mixed short shallow neuro-analgesia, and short analgesia anaesthesia. Psycho-aptitudinal recovery was evaluated with three graphic tests. The results indicate that recovery times are much shorter for shallow neuro-analgesia, and particularly for analgesic anaesthesia by comparison with ordinary shallow techniques coupled with maintenance in O2 + N2O + Halothane.
