Effects of halothane on DNA synthesis and mitosis in root tip meristems of Vicia faba

The effects of halothane on the DNase I activity in an isolated enzyme preparation and in the DNase I-G actin complex

The effects of halothane on the DNase I activity in an isolated enzyme preparation and in a DNase I-globular (G) actin complex was investigated. DNase I, DNase I-G actin complexes and G actin were exposed to various (0.2-4.0 vol./%) halothane concentrations for 3 h. Thereafter, DNase I was mixed with a DNA solution and the extinction of the acid soluble supernatant of the DNase I assay was determined as a measure of DNase I activity. After 10 min of halothane exposure the DNase I activity is inhibited in direct proportion to halothane concentrations between 0.6 and 4.0 vol/%. After 10 min halothane activates inactive DNase I by inhibiting G actin, an inhibitor of DNase I. G actin, exposed to halothane, does not inhibit the activity of DNase I. The results suggest a mechanism by which halothane may contribute to chromosomal defects and disturbances of DNA metabolism in cells.

Effect of halothane anaesthesia on primary antibody response in the chicken

The effect of a single anaesthesia of 2 hours' duration with 1% v/v halothane and of 1, 2, and 3 hours' duration with 2% v/v halothane was studied on the primary antibody response in line-bred chickens. In contradistinction to earlier studies, the immunisation was performed during anaesthesia to resemble antigenic exposure in surgical practice. The IgG and IgM antibodies against the antigens, bovine serum albumin (BSA) and formalin-killed Brucella abortus organisms (Brucella), were quantified by the enzyme-linked immunosorbent assay (ELISA). The halothane concentration of the blood was measured by gas chromatography at the end of anaesthesia. Anaesthesia with 1% and 2% v/v halothane given in the antigen-processing phase of humoral immune response had no effect on the concentrations of IgG-and IgM-anti-BSA and IgG-and IgM-anti-Brucella antibodies in the primary antibody response.

The effect of halothane anaesthesia on liver regeneration

The effects of halothane and diethyl ether on the regenerating liver following 70 per cent hepatectomy were studied in Fisher/344 (F) rats. Our aim was to discover whether halothane administered repeatedly and over prolonged periods could influence the liver regenerative process or hepatocyte function. We also wished to know if the effects of halothane differed from those of diethyl ether. We found: 1. Prolonged halothane or diethyl ether anaesthesia did not inhibit liver mitotic activity, even if administered repeatedly. 2. The effects of halothane and diethyl ether on liver cell division were identical. 3. With reference to liver regeneration, halothane is as safe as diethyl ether when administered during extensive hepatectomy.

The induction of chromosomal abnormalities by inhalational anaesthetics

When Vicia faba root tips are exposed for 2 h to clinically useful concentrations of halothane or methoxyflurane in air, or to halothane in 80% nitrous oxide/20% oxygen, there is a transient increase in mitotic index and then abnormal interphase cells are produced in proportion to the anaesthetic concentrations. After exposure there is a period of mitotic inhibition during which the cells become partially synchronised. When colchicine-metaphase cells collected 28 h after exposure are compared with controls and with metaphases collected only 4 h after exposure, they show a significant increase in the incidence of aneuploidy, tetraploidy and the results of chromosome breakage. It is suggested that all the abnormalities seen can be accounted for by the effects of the anaesthetics on spindle movements, and that at the concentrations used the anaesthetics have no mutagenic effects on chromosomes in interphase.