Effect of voluntary exercise and food restriction in response to lipopolysaccharide in hamsters.

We tested the hypothesis that voluntary running and moderate food restriction alter the acute phase response (APR), one index of nonspecific immune function. Hamsters were kept sedentary or permitted to run and were fed ad libitum or had food restricted for 20 days and were then injected intraperitoneally with saline or lipopolysaccharide (LPS). Fever and circulating interleukin-6, serum amyloid A (SAA), serum iron, and cortisol were measured by biotelemetry, B-9 cell growth assay, indirect enzyme-linked immunosorbent assay, colorimetric analysis, and radioimmunoassay, respectively.

Effect of exercise and food restriction on selected markers of the acute phase response in hamsters.

Acute aerobic exercise has been shown to elicit physiological changes characteristic of the acute phase response (APR), a nonspecific host defense response. Regular evocation of these changes may prime the immune system to improve resistance to disease. Because food deprivation is associated with an impaired APR, food restriction may prevent these beneficial changes.

How well do older persons tolerate moderate altitude?

We studied the physiologic and clinical responses to moderate altitude in 97 older men and women (aged 59 to 83 years) over 5 days in Vail, Colorado, at an elevation of 2,500 m (8,200 ft). The incidence of acute mountain sickness was 16%, which is slightly lower than that reported for younger persons. The occurrence of symptoms of acute mountain sickness did not parallel arterial oxygen saturation or spirometric or blood pressure measurements.

Cytokines and the acute phase response to influenza virus in mice.

This study characterized selected aspects of the acute phase response after intranasal inoculation of mice with two doses of mouse-adapted influenza virus differing in lethality. Mice given 140 plaque-forming units (PFU) of virus (58% survival) gradually decreased food and water intake to nearly zero over 6 days; survivors then slowly increased intakes. Declines in these behaviors were parallel to decreases in body temperature and general locomotor activity and were associated with elevated activities of interleukin-6 (IL-6), tumor necrosis factor-alpha, and interferons in lung lavage fluid.

Interactions between cellular respiration and thermoregulation in the paramecium.

An important adaptation to hypoxia is a regulated reduction in body temperature because it lowers metabolic rate when oxygen supply is limited. Although this beneficial response occurs in organisms ranging from protozoans to mammals, little is known of the cellular mechanisms responsible for the hypoxia-induced reduction in temperature. Using the unicellular protozoan, Paramecium caudatum, we showed that inhibition of oxidative phosphorylation with sodium azide (NaN3) under normoxic conditions mimics the thermoregulatory effects of hypoxia, causing this species to select a lower temperature in a thermal gradient (P < 0.

Responses of salivary acinar cells to intracellular alkalinization.

Responses of rat submandibular acini to intracellular alkalinization were investigated. Intracellular alkalinization was induced by addition of NH4Cl or methyl amines, or by prepulse with Na butyrate. Only partial recovery occurred following Na butyrate prepulse or methylated amine addition, but full recovery was observed following addition of NH4Cl.

Muscarinic signaling pathway in submandibular cells of adult and early postnatal rats.

Elements of the muscarinic signal transduction pathway were compared in submandibular acinar cells of 1-day-old, 1-week-old, and adult rats after exposure to concentrations of acetylcholine ranging from 0.05 to 10 microM. Formation of inositol trisphosphate (IP3) and intracellular Ca2+ were comparable in cells from the three age groups after exposure to agonist concentrations < 1 microM.