Effect of cyclosporin A on rat kidney catecholamines

The immunosuppressive agent, Cyclosporin A, (CsA) has been associated with nephrotoxicity and hypertension. The mechanism for these effects are not known. We therefore determined the levels of the catecholamines; epinephrine (EPI), norepinephrine (NE) and dopamine (DA) and some of their metabolites; epinine, dihydroxyphenyl-acetic acid (DOPAC), homovanillic acid (HVA), metanephrine (ME) and 3-methoxy-4-hydroxy-phenylglycol (MHPG) in the kidneys of rats treated intraperitoneally with either CsA (120 micrograms/kg/body wt/day) or control vehicle (1 ml olive oil/kg body wt/day). Six control or CsA treated rats were sacrificed at 1 hour or 24 hours after a single treatment or after 7 days of daily treatment. Renal catecholamine levels were determined using HPLC-amperometric detector. Treatment with CsA increased renal NE and EPI levels by 59% and 70% respectively within 1 hour. In the rats sacrificed 24 hours after treatment, renal NE, EPI and DA levels were similar to or less than the control levels. Treatment with CsA for 7 days resulted in marginal increases in renal NE (22%) and EPI (30%). These changes were associated with a significant decrease in the levels of catecholamine metabolites in the CsA treated kidneys as compared to the controls. The above findings suggest that increases in renal catecholamines may be involved in the CsA-induced hypertension and nephrotoxicity, perhaps by increasing renovascular resistance.     

Lidocaine pharmacokinetics during water immersion in normal humans

Water immersion produces a marked diuresis, natriuresis, and kaliuresis in association with suppression of the renin-aldosterone system. These effects are mediated primarily by an increase in central blood volume. Consequently, this redistribution and the resultant marked increase in cardiac output is associated with alterations in the circulating levels of several volume regulatory hormones, including plasma renin activity and plasma aldosterone. Although the changes in these blood hormonal levels probably reflect perturbation of hormonal release, it is conceivable that the above-mentioned central hemodynamic modifications result in an altered splanchnic blood flow, thereby modulating hormonal clearances. We assessed the effects of immersion on hepatic blood flow by determining the pharmacokinetics of single doses of lidocaine administered intravenously. Seven normal male subjects were studied during a time-control period and during water immersion to the neck. The clearance of lidocaine was unaltered by immersion, suggesting that the presumed marked central hypervolemia and increased cardiac output was not associated with changes in splanchnic blood flow.     

Purification and properties of human lymphocyte activating factor (LAF).

Lymphocyte-activating factor (LAF) has been shown to be produced by LPS-stimulated human adherent cells (monocytes) and peripheral leukocytes, but many non-macrophage cell lines failed to produce LAF. Other macrophage activators including latex microspheres, antigen-antibody complexes, and barium sulfate induce the production of LAF. There is a delay of 6 hr before significant amounts of LAF activity appear in the supernatant medium and maximum activity is found after 12 to 24 hr. Chromatography of concentrated crude supernatant fractions containing LAF activity on Sephadex G-100 gave two peaks of activity (approximately 85,000 and 13,000 daltons). The latter constitutes the major activity and has been purified at least 500-fold with Sephadex G-100, anion exchange, and adsorption chromatography. Optimal stimulation with LAF induces mitosis in 10% of murine thymocytes. The purified activity is sensitive to chymotrypsin and is not affected by treatment with sodium periodate, sulfhydryl reagents, and phenylmethanesulfonylfluoride. The response of thymocytes to LAF decreases with age after 10 weeks and thymocytes obtained from animals injected with cortisone or tumor-bearing animals have an increased responsiveness to LAF.     

Preparation of lymphocyte-activating factor from continuous murine macrophage cell lines

Lymphocyte-activating factor (LAF), a mitogen for thymocytes and T lymphocytes, is released into the culture medium by human mononuclear cells and mouse peritoneal exudate cells following treatment with various macrophage stimulants. Experiments were performed to determine if recently described mouse macrophage cell lines released LAF in response to stimulation with bacterial lipopolysaccharide. Four continuous cell lines (P388-D₁, J774, WEHI 3, and PU5-1.8) were found to release LAF in serum-free medium following endotoxin stimulation. The results of partial purification indicated that LAF obtained from cell lines had a higher molecular weight and lower isoelectric point than LAF from human mononuclear cells.