Synchrony in the amphibian lymphatic system: evidence for bilateral posterior lymph heart synchrony and cardiac–lymphatic synchrony inRana catesbeianaandBufo marinus

Abstract

Early investigations into amphibian lymph heart function established that lymph heart contractions were synchronous with neither the systemic heart, nor the lungs, nor each other. However, the present study concludes that there is synchronization between the cardiac heart and the lymph hearts and that the posterior lymph hearts in both Rana catesbeiana Shaw, 1802 and Bufo marinus (L., 1758) beat synchronously as well. Pressure peaks were recorded through cannulation of the ischiatic artery and each posterior lymph heart and subsequently analyzed to determine the time differences between arterial diastole and lymph heart systole or between two bilateral lymph heart systoles. Results show that there is clear synchronization between the lymph heart systoles of two bilateral posterior lymph hearts. This lymph heart synchrony is further supported by using Poincaré plot analysis to visually compare the lymph heart inter-beats. Cardiac heart and lymph heart contractions also show a degree of synchronization, even though the lymph hearts beat up to three times as fast as the cardiac heart. These results support the conclusion that synchrony is characteristic of the anuran lymphatic system and that synchronization of the cardiac heart and the lymph hearts could impart an energetic advantage that benefits fluid homeostatic mechanisms.