Meeting Abstract

14.4  Jan. 4  Functional morphology of the python heart STARCK, J.M.; Univ. Munich, Germany starck@uni-muenchen.de

Snakes, like all other ectotherm sauropsids, have a complicated heart anatomy, with five functional chambers: left and right atrium, the Cavum arteriosum, the C. venosum and the C. pulmonale. The C. venosum and C. pulmonale are connected by a wide opening, but, during ventricular systole, are functionally separated by a muscular ridge. The C. arteriosum has no arterial exit but ejects oxygenated blood through an intraventricular canal into the C. venosum and C. pulmonale. A current functional hypothesis suggests that the muscular ridge acts as central shunt that directs oxygenated blood from the C. arteriosum into the left and right aorta, and deoxygenated blood from the right atrium through the C. pulmonale into the pulmonary artery. The direction of the shunt supposedly is condition dependent (e.g., hypoxic vs normoxic; digesting vs fasting). I have studied the functioning of the heart of ball python (Python regius; N=6 adult individuals) by (I) investigating the specific heart anatomy by macroscopic dissections and microscopic anatomy, and (II) by using non-invasive Doppler-ultrasonography to record direction, velocity, and volume of the blood flow during the heart cycle, and in different physiological conditions of the snake, i.e., fasting vs. digesting. Oxygen consumption of the snakes was recorded simultaneously to the Doppler-ultrasonography by open flow respirometry. The dynamic functioning of the muscular ridge and the arterial valves, the pattern of blood flow in the heart, and the separation of the blood stream into the three major arteries are described using real time Doppler-ultrasonography records from live snakes. Quantitative measures of blood flow volume in the left and right aorta, and in the pulmonary artery are given for fasting and digesting snakes. The functional significance of the muscular ridge and concepts of central shunting are discussed.