Intercellular ultrafast Ca2+ wave in vascular smooth muscle cells: numerical and experimental study

Abstract

Vascular smooth muscle cells exhibit intercellular Ca2+ waves in response to local mechanical or KCl stimulation. Recently, a new type of intercellular Ca2+ wave was observed in vitro in a linear arrangement of smooth muscle cells. The intercellular wave was denominated ultrafast Ca2+ wave and it was suggested to be the result of the interplay between membrane potential and Ca2+ dynamics which depended on influx of extracellular Ca2+, cell membrane depolarization and its intercel- lular propagation. In the present study we measured experimentally the conduction velocity of the membrane depolarization and performed simulations of the ultrafast Ca2+ wave along coupled smooth muscle cells. Numerical results reproduced a wide spectrum of experimental observations, including Ca2+ wave velocity, electrotonic membrane depolarization along the network, effects of inhibitors and independence of the Ca2+ wave speed on the intracellular stores. The numerical data also provided new physiological insights suggesting ranges of crucial model parameters that may be altered experimentally and that could significantly affect wave kinetics allowing the modulation of the wave characteristics experimentally. Numerical and experimental results supported the hypothesis that the propagation of membrane depolarization acts as an intercellular messenger mediating intercellular ultrafast Ca2+ waves in smooth muscle cells.

The first digestive movements in the embryo are mediated by mechanosensitive smooth muscle calcium waves

“…similar to the speed of cytosolic calcium fertilization waves [16] and 2 -3 orders of magnitude slower than embryonic heart (approx. 20 mm s 21 [17,18]) or arterial smooth muscle (5 -15 mm s 21 , [19]) calcium waves. The fact that the circumferential (along the fibre axis) propagation speed is higher than the longitudinal ( perpendicular to the fibre axis) speed (figure 1f ) is consistent with previous measurements on adult gut [20].…”

“…The calcium up-rise is probably due to influx from the extracellular medium due to disruption of membrane integrity after wounding [24,25], and has been shown to orchestrate wound healing [23,26]. (4) Calcium waves can be elicited in smooth muscle cell cultures by gentle mechanical stimulation [19,27]. Bayliss & Starling [28] discovered more than a century ago that peristalsis movements in the adult (dog) intestine can be triggered by pinching or inserting bolus.…”

“…Calcium waves can be elicited in smooth muscle cell cultures by gentle mechanical stimulation(19,27).Bayliss & Starling(28) discovered more than a century ago that peristalsis movements in the adult (dog) intestine can be triggered by pinching or inserting bolus. The insertion of a bolus results in contraction of the muscle coat above the bolus, and its relaxation downward of the bolus.…”