Contributions on cardiac physiology in Diplopoda (Myriapoda)

Investigations into cardiac physiology in Myriapoda are rare, but heart beat generation is not considered to be uniform throughout this taxon. Although cardiac automatism in Chilopoda is neurogenic, superimposed onto a myogenic automatism, the present study reveals, on the basis of electrophysiological experiments including electrocardiograms and the first intracellular recordings from dorsal vessel muscle cells of Archispirostreptus gigas Peters, 1855 (Diplopoda: Spirostreptida, Spirostreptidae), that heartbeat generation in Diplopoda is clearly myogenic. Experiments with tetrodotoxin confirm this result, and also show that proctolin, acetylcholine and octopamine have no effect. The results are discussed from the perspective of comparative cardiac physiology in arthropods.