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Cardiac autonomic innervation of the western pygmy possum (Cercatetus concinnus) and golden bandicoot (Isoodon auratus)
journal contributionposted on 2023-05-18, 21:05 authored by Graeme ZoskyGraeme Zosky, O'Shea, JE
Evidence for a functional ventricular parasympathetic innervation of the mammalian heart between and within taxa remains controversial. We have previously proposed that the presence of a functional parasympathetic innervation of the ventricle was indicative of heterothermy, and is essential for maintaining ventricular stability at low body temperature. However, it is possible that the presence of such an innervation is also representative of the primitive mammalian state. In this study, we aimed to determine whether a functional parasympathetic innervation of the ventricle, that is capable of actively reducing the force of contraction, is present across metatherian mammals. Using in vitro isolated cardiac preparations, we examined evidence for a functional ventricular parasympathetic innervation of the ventricle in two species of metatherian mammal, one heterotherm (Western pygmy possum; Cercatetus concinnus) and one homeotherm (Golden bandicoot; Isoodon auratus), from different families to complement existing data from a heterothermic dasyurid. Both C. concinnus and I. auratus had a potent biphasic response to transmural electrical stimulation in both atrial and ventricular preparations. Both the decrease and increase in the force of contraction in response to stimulation were almost entirely blocked by the cholinergic and adrenergic antagonists, atropine and propranolol, respectively. These observations provide clear evidence for a parasympathetic innervation of the ventricle that is capable of directly influencing the force of contraction across metatherian mammals with different thermoregulatory strategies. While this innervation may facilitate heterothermy, this suggests that the presence of such an innervation pattern is indicative of the primitive mammalian state.
Publication titleJournal of Comparative Physiology Part B: Biochemical, Systemic, and Environmental Physiology
Department/SchoolTasmanian School of Medicine
Place of publication175 Fifth Ave, New York, USA, Ny, 10010
Rights statementCopyright 2016 Springer-Verlag Berlin Heidelberg