Oxygen uptake, respiratory exchange ratio, or total distance: a comparison of methods to equalize exercise volume in Wistar rats

This study compared strategies to equalize the volume of aerobic exercise performed with different intensities by Wistar rats, based on the distance covered during exercise bouts and energy expenditure (EE, isocaloric sessions) obtained from oxygen uptake (V̇O2) or respiratory exchange ratio (RER). Thirty-three male rats (270.5±12.8 g) underwent maximal exercise tests to determine V̇O2 reserve (V̇O2R), being randomly assigned to three groups: moderate-intensity continuous exercise at speed corresponding to 50% V̇O2R (MIC; n=11); high-intensity continuous exercise at 80% V̇O2R (HIC; n=11); and high-intensity intermittent exercise (HII; n=11) at 60% V̇O2R (3 min) and 80% V̇O2R (4 min). Exercise duration was calculated individually to elicit EE of 5 kcal in each session. No difference between groups was found for total running distance (MIC: 801±46, HIC: 734±42, HII: 885±64 m; P=0.13). Total EE measured by RER was systematically underestimated compared to values obtained from V̇O2 (HII: 4.5% and MIC: 6.2%, P<0.05). Total EE (calculated from V̇O2), and duration of HIC bouts (2.8 kcal and 30.8±2.2 min) were lower (P<0.0001) than in MIC (4.9 kcal and 64.7±1.8 min) and HII (4.7 kcal and 46.9±2.2 min). Predicted and actual values of total V̇O2, total EE, and duration of isocaloric sessions were similar in MIC and HII (P>0.05), which were both higher than in HIC (P<0.0001). In conclusion, the time to achieve a given EE in exercise bouts with different intensities did not correspond to the total distance. Therefore, the volume of aerobic exercise in protocols involving Wistar rats should be equalized using EE rather than total covered distance.

Effects of hypertonic NaCl solution on the hamster cheek pouch microcirculation in normo- and hypovolemia

The aim of this study was evaluate the effects of a single, 10 min, intravenous infusion of a hyperonic NaCl solution [2.400 mOsm/l; infused volume 0.35 ñ 0.03 ml (SEM) on the hamster cheek pouch microcirculation during normovolemia and after acute bleeding to a hypotension level of about 40 mmHg. Upon bleeding, the arterial pressure dropped to 39 µ 1 mmHg, arterioles > 40 -m constricted 12 ñ 3% (from their control value), arterioles < 40 µm dilated 6 ñ 2%, venules stayed largely unchanged, while RBC velocity and volume flow decreased 57 ñ 7% in all vessels. Durign the subsequent hypertonic NaCl infusion, the arterial pressure increased rapidly to a new steady state level of 66 ñ 3 mmHg. After the infusion, the large arterioles stayed constricted 11 ñ 1% and the small arterioles dilated 7 ñ 1% for a 1-h observation period. The venules constricted iniatially by 6 ñ 2% and returned to control diameter in 30-40 min. RBC velocity and calculated volume flow returned to the pre-hemorrhage cotrol values in about 10 min for the arterioles and in 40 min for the venules. An identical hypertonic infusion given to normovolemic hamsters caused no significant alterations of the measured variables

Nailford capillaroscopy in diabetes mellitus: morphological abnormalities and relationship with microangiopathy

the morphology and density of nailfold capillaries were evaluated in patients with Type I and Type II diabetes mellitus and in healthy controls, using videocapillaroscopy. A protocol of well-defined capillary patterns was used. Diabetic patients had more tortuous and enlarged capillaries than controls. Nodular apical elongation was found only in diabetics and was more frequent in patients with a longer history of disease. Type II diabetic patientes with chronic clinical complications had a higher frequency of enlarged capillaries and nodular apical elongation. Glycemic control was without influence. Capillary densitu did not differ among the groups