Developmental physiology of cardiac contraction in the Japanese newt in vivo and in vitro.
Development and differentiation of whole hearts of larvae of an experimental amphibian species, the Japanese newt (Cynops pyrrhogaster), were studied in vitro and in vivo with particular reference to cardiac contraction, its temperature sensitivity and morphology. Hearts cultured in the solid or flat state in plastic flasks for 27 days developed from stage 35 to stage 55 and corresponded closely to in vivo developing hearts with respect to morphologic criteria and temperature sensitivity of cardiac contraction. The peak rate of contraction at room temperature occurred after 20 days, both for cultured hearts in vitro and for in vivo hearts, which had reached stage 50 to 52 of development. Excised fractions of heart continued to beat at reduced rates for extended periods. Hearts cultured at late stages (50 to 55) continued to beat for 282 days, though the rate decreased to 1 bpm. Although cardiac contraction rate gradually declined during long-term culture, the sensitivity of this tissue to temperature change remained constant for 250 days. Thus, culture of the heart of this species should prove useful to the investigation of factors related to induction and developmental regulation of contractility.
Uehara
M
M
Department of Pediatrics, Faculty of Medicine, Teikyo University, Tokyo, Japan.
Taguchi
M
M
Asashima
M
M
Pfeiffer
C J
CJ
D000818:Animals; D006321:Heart / Q000254:growth & development* / Q000502:physiology; D007814:Larva; D009200:Myocardial Contraction; D009924:Organ Culture Techniques; D012455:Salamandridae / Q000254:growth & development / Q000502:physiology*; D013696:Temperature