Intercellular communication controls agonist-induced calcium oscillations independently of gap junctions in smooth muscle cells.

Abstract

We report the existence of a unique mode of communication among human smooth muscle cells (SMCs) where they use force to frequency modulate long-range calcium waves. An important consequence of this mechanical signaling is that changes in stiffness of the underlying extracellular matrix can interfere with the frequency modulation of Ca2+ waves causing healthy SMCs to falsely perceive a much higher agonist dose than they actually received. This distorted sensing of contractile agonist dose on stiffer matrices is absent in isolated SMCs, even though the isolated cells can sense matrix rigidity. We show that intercellular communication that enables this collective Ca2+ response does not involve transport across gap junctions or extracellular diffusion of signaling molecules. The aberrant communication between cells that distorts the individual cell's perception of contractile stimulus can explain the sudden, exaggerated narrowing of the lumen when exposed to low dose of inhaled agonists in diseases like asthma.