The purpose of this study was to determine if the accumulation of the 72-kDa heat shock protein (HSP70) is elevated in response to a prolonged bout of submaximal exercise in which colonic temperature (Tco) remained at control levels. Sprague-Dawley rats were randomly assigned to one of four testing groups [n = 8 per group; ambient temperatures (Ta) for each condition are included]: 1) control (cool/rest; Ta = 24 degrees C); 2) cool and exercise (cool/exercise; Ta = 14 degrees C); 3) nonexertional heating (heat/rest; Ta = 42 degrees C); 4) heat and exercise (heat/exercise; Ta = 32 degrees C). All interventions were approximately 60 min in duration. An exercise bout consisted of treadmill running at 17 m/min and 0% grade, while the heat/rest and heat/exercise experiments consisted of heat exposure that was terminated when Tco reached 41 degrees C. Baseline Tco was similar for all four groups. In the cool/rest and cool/exercise groups, final Tco was not different from the baseline values, nor was it different between these two groups. In the heat/rest and heat/exercise groups, heating rates were similar. Tissue samples were obtained from the gastrocnemius, soleus, and extensor digitorum longus (EDL) muscles of the left hindlimb and the left ventricle 30 min after a trial was completed. An enzyme-linked immunosorbent assay specific for HSP70 was used to directly quantitate absolute levels of HSP70 in tissues. There were significant main effects of both heating and exercise for HSP70 levels in the gastrocnemius, soleus, and left ventricle (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

SUMMARY A duplex scanner which consists of a real time two dimensional scanner and a pulsed Doppler flowmeter was used to measure superior mesenteric blood flow in 70 healthy subjects. By processing the Doppler shift signals, the instantaneous average Doppler shift frequency and then the instantaneous average velocity of the flow rate were calculated. Both diameter of the vessel and angle between vessel and beam were measured from real time imaging. The mean (+ standard error of the mean) of the superior mesenteric blood flow was 517±19 ml/min. There was neither significant difference in flow between sexes, nor correlation between flow and age (r=0.042). The mean of coefficients of variability were 6-8% over the short term, and 8.2% in long term studies.The superior mesenteric artery supplies blood to the duodenum -except for its superior portion -and also to the whole of the small bowel and the right half of the colon. Little information is available concerning superior mesenteric artery blood flow (SMABF)

To determine whether aging results in reduced accumulation of the 70-kDa heat shock protein (HSP70) in response to a thermal challenge, experiments were conducted in conscious and freely moving mature (12-mo-old) and senescent (24-mo-old) male Fischer 344 rats. Rats were assigned to a euthermic control group or a nonexertionally heated group that was exposed to an ambient temperature of 42 degrees C until colonic temperature reached 41 degrees C. Samples were subsequently obtained from the liver and myocardium, and absolute levels of both the constitutive and inducible forms of HSP70 were quantitated. Heat-stressed rats had significantly elevated HSP70 levels in the liver compared with the euthermic groups. Post hoc comparisons revealed that heat stress elicited marked elevations in liver HSP70 in mature rats compared with age-matched control animals. In contrast, HSP70 values were unchanged in the senescent heated group vs. the control group. In the myocardium, heat stress produced marked increases in HSP70 levels in both the mature and senescent groups compared with age-matched control animals, with accumulation significantly blunted in the senescent vs. mature rats. Thus the increases in liver and myocardial HSP70 accumulation in response to nonexertional heat stress are attenuated with senescence. Because these proteins are postulated to protect cells from injury and enhance cellular recovery from heat stress, the data suggest that an aging organism has a reduced ability to properly maintain cellular function and integrity after a thermal challenge.

No abstract

No abstract