Whole-body pre-cooling does not alter human muscle metabolism during sub-maximal exercise in the heat

Muscle metabolism was investigated in seven men during two 35 min cycling trials at 60% peak oxygen uptake, at 35 degrees C and 50% relative humidity. On one occasion, exercise was preceded by whole-body cooling achieved by immersion in water during a reduction in temperature from 29 to 24 degrees C, and, for the other trial, by immersion in water at a thermoneutral temperature (control, 34.8 degrees C). Pre-cooling did not alter oxygen uptake during exercise (P > 0.05), whilst the change in cardiac frequency and body mass both tended to be lower following pre-cooling (0.05 < P < 0.10). When averaged over the exercise period, muscle and oesophageal temperatures after pre-cooling were reduced by 1.5 and 0.6 degrees C respectively, compared with control (P < 0.05). Pre-cooling had a limited effect on muscle metabolism, with no differences between the two conditions in muscle glycogen, triglyceride, adenosine triphosphate, creatine phosphate, creatine or lactate contents at rest, or following exercise. These data indicate that whole-body pre-cooling does not alter muscle metabolism during submaximal exercise in the heat. It is more likely that thermoregulatory and cardiovascular strain are reduced, through lower muscle and core temperatures.

Additions to the technique of epi-illumination light microscopy for the study of floral and vegetative apices

Various staining techniques for apices destined for epi-illumination light microscopy are described and discussed. Appropriate modifications to photographic procedures are described. A technique is described for the subsequent observation of specimens in a scanning electron microscope fitted with a cryo-stage.

Simultaneous pair-feeding system for the administration of alcohol-containing liquid diets

We present studies in which a new, simultaneous pair-feeding system is utilized to administer alcohol-containing liquid diets to rats. In this system, consumption of an alcohol-containing diet by an animal leads to the corresponding delivery of the same amount of control diet to a control animal, which avidly consumes its diet upon presentation. Thus, circadian nutritional pairing is possible, avoiding the long period of fasting to which control animals are exposed, on a daily basis, when the diets are administered by the conventional pair-feeding system with Richter tubes. The new system does not require actual daily measurement of the diet consumed by the ethanol-fed animal and allows the conservation of the diet for prolonged periods, thus not requiring daily diet changes. The feeding system also allows the pair-feeding of more than one simultaneous control and can be adapted to a number of other fluids and to other animals species, when paired delivery of the fluid is desired.