Basic Electrophysiological Properties of Cells in the Organ Surface Primo Vascular Tissues of Rats

Abstract

The primo vascular system (PVS) is a novel circulatory system composed of primo vessels and primo nodes, and its morphological and functional properties are largely unknown. In this study, we characterized basic electrophysiological properties of the cells in the primo vessels and primo nodes on the surface of abdominal organs. The electrophysiological activities of the cells in the primo vessels and nodes were studied by intracellular recording technique with sharp electrodes and by whole-cell slice patch recording techniques, respectively. The cells of the primo vessels and nodes did not exhibit spontaneous activities or action potentials. The resting membrane potentials of the primo vessel and node cells were −21.14 ± 2.24 mV (n = 35) and −36.69 ± 1.38 mV, respectively (n = 67). The current-voltage relations of the primo vessel cells were linear, but those of the primo node cells were outwardly rectifying. Morphologically, most primo vessel cells showed a round shape, but a small portion of cells showed a longitudinal one. In contrast, most cells in the primo node slices were round-shaped, and the longitudinal cells were not observed. Taken together, the results indicate that the cells in the PVS tissues are electrophysiologically and morphologically heterogenous, and that the small round cells that are most abundant in the primo vessels and nodes are nonexcitable.