The effect of naloxone on the preoperative gastric volume and pH

The effect of 4 mg oral naloxone on preoperative gastric volume and pH of gastric aspirate was studied in a double-blind, randomized study. Twenty patients received 10 ml of naloxone (4 mg) mixed with 10 ml of orange juice, and 20 patients received 10 ml of isotonic saline mixed with 10 ml of orange juice, 2 h before surgery. Gastric content was obtained immediately after intubation of the trachea. No significant difference in gastric volume and pH of gastric aspirate was found between the two groups. It is concluded that naloxone does not affect gastric emptying and gastric acid secretion to a degree great enough to protect against aspiration of gastric contents into the lungs.     

Plasma Histamine After Methacholine, Allergen, and Aspirin Challenges

Plasma histamine levels were measured by radio-enzymatic technique in seven patients following 10 challenges: five methacholine challenge tests, four antigen inhalation challenge tests, and one oral aspirin challenge test. Baseline plasma histamine was the same in all patients except in the aspirin-challenged patient, who had a higher baseline histamine level. There was no statistical change in the level of histamine throughout the test in either the methacholine-challenged or the antigen-challenged patients, whereas there was a marked increase in histamine levels in the aspirin challenged patient. A possible explanation is that methacholine and antigen are inhaled and therefore have primarily local effects on the lung, whereas oral aspirin has a systemic effect with consequently systemic changes in histamine which are detectable as changes in plasma level.     

Generation of platelet activating factor (PAF) by a human lung epithelial cell line

A human lung epithelial cell line (ATC-CCL-185) was cultured in nutrient Ham-F12 medium. Cells in monolayers were stimulated with either ionophore A23187 (1 microM) or phorbol myristate acetate (PMA, 0.2 microM) for various periods of time. Samples were analysed by HPLC and the presence of platelet activating factor (PAF) was detected by bioassay of the release of [3H]serotonin from rabbit platelets undergoing aggregation. The ATC-CCL 185 cells were found to synthesize PAF following activation with either PMA or ionophore. Ionophore at 1 microM was found to be more potent than PMA at 0.2 microM in the induction of PAF synthesis (congruent to 80 ng/mg protein). The synthesis of PAF through ionophore stimulation reached a maximum at 5 min, whereas PMA stimulation peaked at 15-20 min. PMA induced approximately one third the level of PAF synthesis by the ionophore. The PAF synthesized by these CCL185 cells was found to be mainly associated with the cell membrane with less than 10% released into the medium. Release of PAF into cell supernatant was dependent on the presence of bovine serum albumin (BSA). In the absence of BSA, a large portion (approximately 90%) of PAF was found to be cell associated, and only 60% when BSA concentration reached greater than or equal to 0.2%. These results demonstrate the ability of this lung epithelial cell line to synthesis PAF thus, suggesting that epithelial cells might participate in the process of inflammatory lung diseases, through the generation of this important mediator.