Respiratory consequences of feeding in the snake Python molorus

Area of Science:

• Physiology
• Herpetology
• Comparative Physiology

Background:

• Snakes exhibit significant metabolic rate increases post-feeding.
• Digestion studies offer insights into reptilian cardio-respiratory responses to high metabolic demands.

Purpose of the Study:

• To investigate the effects of large meal ingestion on metabolic rate, arterial oxygen levels, and acid-base status in Python molorus.
• To compare the physiological response of pythons during digestion with other ectothermic vertebrates.

Main Methods:

• Four Python molorus snakes were surgically fitted with cannulas in the dorsal aorta.
• Blood samples were collected over 72 hours post-feeding (a meal exceeding 20% of body weight).
• Measurements included oxygen consumption, respiratory gas exchange ratio, plasma lactate, arterial blood gases (PO2, PCO2), and acid-base parameters.

Main Results:

• Oxygen consumption increased nearly fourfold post-feeding, met by aerobic respiration (plasma lactate < 0.5 mM).
• Arterial PO2 and hemoglobin-O2 saturation remained stable, despite a decrease in hematocrit due to sampling.
• Plasma bicarbonate increased, but stable arterial PCO2 maintained a consistent arterial pH, unlike in alligators.

Conclusions:

• Pythons demonstrate a unique physiological response to digestion, with stable blood gases despite a substantial increase in metabolic rate.
• The observed differences in acid-base regulation compared to alligators highlight interspecific variations in reptilian digestive physiology.
• Further research into arterial blood gas dynamics during digestion across diverse ectothermic species is warranted.