Capillary pericytes in cochlear lateral wall express strong Kir current and electrical coupling suggest its role in K+‐mediated local blood flow regulation

Abstract

Microvessels in spiral ligament (SL) and strial vascularis (SV) are densely populated with pericytes (PC) but their functioning mechanisms are not well understood. Using capillary segments isolated from guinea pig cochlear lateral wall and whole‐cell recording techniques, we found the PCs showed a robust inward K+‐current, which would play a key role in regulation of local blood flow.Results1) With physiological solutions, the PCs, but not the endothelial cells (EC), showed a Ba2+‐sensitive inward rectification in I/V domain <‐60 mV. [K+]o 20 mM enhanced the rectification and induced a ~15 mV hyperpolarization. 2) The PCs’ input conductance and capacitance indicated an 18β‐glycyrrhetinic acid‐sensitive electrical coupling. 3) TEA and 4‐AP showed little effect on IV relations. 4) La3+ and niflumic acid (0.1 mM) slightly reduced I/V slope with a net current reversal potential ~−15 and 0 mV, respectively. 5) Acetylcholine, norepinephrine, nitrendipine and glipizide caused no significant change in I/Vs or membrane potentials in the PCs. We conclude that local physio‐pathological [K+]o fluctuation can act on Kir and regulates PC's membrane potential and thus its motor tone. By this mechanism and the spreading effect of gap junction coupling, the PCs may sense the level of K+ recycling driven by hair cell acoustic transduction thus to adjust the vasotone and lateral wall blood flow. In addition, cholinergic and adrenergic neuro factors may play little role in the microcirculation control at PC level. Supported by NIH grants R01 DC004716 (ZGJ) and DC00105 (ALN).