The American journal of physiology
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Diethyl maleate (DEM, 0.025-0.10 mM) increased glutathione (GSH) levels in calf pulmonary artery endothelial cells up to fivefold in 12-24 h of incubation. Parallel increases occurred in the rates of uptake of cystine and glutamate. The DEM-mediated increases in both GSH levels and glutamate-cystine uptake were inhibited by cycloheximide and actinomycin D, indicating a dependency on protein and RNA synthesis. ⋯ Although the increase in glutamate uptake produced by hyperoxia appeared to be under the regulation of protein synthesis, the relationship with elevated GSH in the presence of hyperoxia was less clear because of elevation of control cellular GSH by cycloheximide or actinomycin D alone. Inhibition of GSH synthesis by buthionine sulfoximine also stimulated cystine and glutamate uptake. We conclude that elevation of endothelial intracellular GSH by both DEM and hyperoxia is associated with and may be produced by enhanced uptake of precursor amino acids; the effect of DEM is more pronounced and more specific than that of hyperoxia.
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To overcome the disadvantages of the presently available hemoglobinometers, we have developed an optical instrument that measures the total hemoglobin (Hb) concentration in whole, undiluted blood. The device uses an infrared light-emitting diode to illuminate a capillary tube filled with a sample of whole blood. Light scattered in the blood travels a short distance down the length of the capillary tube, passes through a second light path, and reaches a photodetector, the output of which is amplified, digitized, and fed into a microprocessor. ⋯ Thus the accuracy appears to be less than 1 g Hb/dl. The advantages of the present device are as follows: 1) no chemical reaction is required (hence neither accurate dilutions nor toxic reagents are necessary); 2) it reads Hb concentration within a few seconds; 3) it can be operated by unskilled personnel; 4) it could be made portable and thus could be operated in the field, in rural settings, or at accident sites; 5) sample size is small (25-70 microliters); and 6) the same capillary tube can be centrifuged if a measure of hematocrit is also desired. A detailed parts list and circuit diagram are presented, and sources of error are discussed.
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To elucidate the cardiovascular effects of alpha-human calcitonin gene-related peptide (CGRP), we infused CGRP intravenously at increasing rates of 3, 10, and 30 pmol.kg-1.min-1 during successive 15-min intervals into intact dogs, cardiac-denervated (CD) dogs, and cardiac-denervated dogs pretreated with beta-blockers. In intact dogs, the initial infusion rate of CGRP at 3 pmol.kg-1.min-1 did not produce significant hemodynamic changes, but the two higher infusion rates produced dose-dependent decreases in total peripheral resistance, mean arterial pressure, and left and right atrial pressures and produced dose-dependent increases in heart rate (HR) and cardiac output (CO). In addition, stroke volume decreased and pulmonary vascular resistance increased at the highest infusion rate. ⋯ In CD dogs pretreated with beta-blockers, CGRP did not increase HR and the increase in CO was further attenuated. In a separate experiment, the lowest dose of CGRP (3 pmol.kg-1.min-1) was infused intravenously for 60 min in intact dogs; significant cardiovascular responses, qualitatively similar to those produced by higher rates of infusion, occurred. We conclude that CGRP is an extremely potent vasodilator and that the increase in HR is mediated primarily by autonomic reflexes.