A new method for obtaining electrocardiograms in unrestrained crocodilian reptiles.

A new procedure is described for acquiring measurements of electrocardiographic parameters in unrestrained crocodilians. These measurements are difficult to obtain in freely moving animals; hence, electrocardiographic activity under natural conditions has not been previously quantified. In this investigation, twelve American alligators were equipped with subcutaneous electrodes. The lead wires were sutured to each animal's skin and the extracutaneous wires coiled and held in place against the animals' dorsal surfaces with waterproof elastic bandages. The electrodes were connected to an ECG analyzer only at the time of measurement. The presence of the leads and harness did not appear to interfere with the movements of the animals either in the animal room or during testing. This method allows for more precise measurements of cardiac activity under conditions which closely resemble those of crocodilians in their natural state.

Glycolysis in Anolis carolinensis during agonistic encounters.

We examined the influences of territorial status, encounter outcome, body mass difference, activity, and display on lactate accumulation in adult male Anolis carolinensis during agonistic interactions. Of the pairs of lizards frozen at the onset of an encounter, intruders had significantly higher lactate concentrations than residents. Lactate levels at the onset of an interaction were not significantly different from those at the conclusion, suggesting a limited role for glycolysis during such events. The outcome of an agonistic encounter was not based on fatigue. Individuals that were larger or changed sites had a lower relative lactate concentration at the conclusion of an interaction than smaller or sedentary animals. We consider the influence of autonomic arousal on glycolysis.

Aerobic and anaerobic metabolism of paired male lizards (Anolis carolinensis).

The associations of physical activity, skin color, body mass difference and conspecific olfactory cues with short-term aerobic and anaerobic metabolism in paired male Anolis carolinesis were examined. Control measurements for mild laboratory manipulation (such as the movement of a metabolic chamber) yielded significant increases in the rate of oxygen consumption, but not in the lactate concentration of these animals; stronger manipulation increased both. A possible influence of conspecific olfactory cues on the metabolism of lizards introduced into empty chambers was undetected. Anolis that turned from green to brown with handling showed an increase in oxygen uptake, but an association between this color shift and total body lactate level was not detected. Elevated rates of oxygen use and glycolysis were found in pairs of males in the absence of physical activity. Lactate levels of the individuals of a pair were positively correlated with one another; the lactate concentrations of lizards placed into occupied metabolic chambers were correlated with the difference in body mass of the pair.

Cardiovascular correlates of exercise in snapping turtles, Chelydra serpentina.

1. Heart rate increased with a rise in body temperature (10-30 degrees C) and with induced physical exercise in snapping turtles. 2. Maximum heart rate increment occurred at 30 degrees C. 3. Standard oxygen pulse did not change with a rise in temperature. 4. Oxygen pulse during exercise and oxygen pulse increment were maximal at 10 degrees C and minimal at 20 degrees C. 5. The increase in heart rate with exercise accounted for only 9-22% of the increase in oxygen transport during activity; the remainder was provided by a rise in cardiac stroke volume and/or A-V difference.

Aerobic metabolism of American alligators, Alligator mississippiensis, under standard conditions and during voluntary activity.

We measured the rate of consumption of oxygen by alligators in a dry metabolic chamber and in a tank of water where they were free to dive and surface at will at 10-35 degrees C, a range spanning most of the body temperatures experienced by alligators in nature. Neither the standard metabolic rate nor the rate of oxygen consumption during one hour of sustained, voluntary activity varied with body mass, month of the year, duration of fasting before measurement, or experimental condition (terrestrial vs aquatic). Voluntary diving is not accompanied by any reduction in standard metabolic rate; these results and those of others suggest that the "diving reflex" of alligators is probably employed only in emergencies. Spontaneous activity for one hour is accompanied by a 1.9-4.4 fold rise in oxygen consumption; this factorial increase is less than that for other reptiles induced to maximal activity for brief intervals. Both standard and active oxygen consumption rise significantly with body temperature.