Effects of hyperbaric oxygen exposure on a zymosan-induced shock model.

OBJECTIVE: 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. DESIGN: Experimental study. SETTING: Institute of Pharmacology and Toxicology, 2nd University of Naples, Naples, Italy. SUBJECTS: 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). MEASUREMENTS AND MAIN RESULTS: 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.

Effects of hyperbaric oxygen exposure on non-adrenergic non-cholinergic responses of rat trachea.

The effects of prolonged (20 day) hyperbaric exposure (HBO) to oxygen on non adrenergic non cholinergic (NANC) contractile and relaxant responses of rat trachea were examined. The electrical field stimulation (EFS) of rat tracheal rings was performed at 30 Hz and contractile and relaxant responses were assessed in the absence or in the presence of pretreatment with L-nitro-arginine-methyl-ester (L-NAME), an inhibitor of NO synthase, and L-Arginine (L-ARG), a precursor of NO synthesis, plus L-NAME. Our data demonstrated that L-NAME significantly (p < 0.05) enhanced the contractile responses induced by EFS (controls 30.6 +/- 0.99%; L-NAME 76.07 +/- 2.00%) and statistically (p < 0.05) reduced the relaxant component of EFS (controls 31.10 +/- 0.46; L-NAME 15.00 +/- 0.12); these effects were reversed when tissues were pretreated with L-ARG plus L-NAME, suggesting that NO plays a modulatory role in cholinergic neurotransmission and participates in EFS relaxant responses. Moreover, prolonged HBO exposure (20 days) at 202.6 and 303.9 kPa did not modify the contractile or relaxant responses induced by EFS, nor modify the L-NAME or L-ARG effects on EFS responses.

Cardiovascular and respiratory effects of dermorphin in rats.

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.

[A technic of analgesic anesthesia as brief anesthesia]. / Una tecnica di anestesia analgesica come anestesia breve.

An original technique of analgesic anaesthesia, with the characteristics of brief and out-clinic anaesthesia, has been experimented in a group of patients undergoing light surgery (eye surgery). The technique employs an association of an analgesic--Fentanil--a low dose hypnotic and marked hyperventilation. Recovery characteristics have been assessed by studying neuromuscular and psychoaptitudinal recovery times (Romberg negativisation). The results show that this technique may be worthily included among the best techniques of brief anaesthesia.

[Study of recovery from anesthesia by means of graphic tests of writing and drawing]. / Studio del recupero dalla narcosi mediante prove grafiche di scrittura e disegno.

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.