Hyperpolarization of Mouse Pulmonary Artery Smooth Muscle and Endothelium by Calcitonin Gene Related Peptide

Abstract

The goal of these experiments was to develop mouse pulmonary arteries (PAs) as a viable model for investigating the electrophysiological actions of the sensory neurotransmitter calcitonin gene related peptide (CGRP) on membrane potential (Vm) and electrical signal transmission in PA smooth muscle cells (SMCs) and endothelial cells (ECs). Intact PAs were isolated from anesthetized male C57BL/6J mice (3 months old). Immunostaining confirmed that PAs were sparsely innervated by sensory nerves containing CGRP. For intracellular recording, intact PAs (diameter, ~150 μm) were cannulated, pressurized to 16 cm H2O and studied at 37°C. Alternatively, SMCs were gently dissociated to obtain intact endothelial tubes studied at 32°C. We tested the hypothesis that CGRP would hyperpolarize SMCs and ECs in a concentration‐dependent manner. During continuous recording of Vm, increasing [CGRP] from 1 nM to 1 μM hyperpolarized SMCs of intact PAs from −34±2 mV (rest) to −52±3 mV and EC of tubes from −37±4 mV (rest) to −58±4 mV (n ≥ 4 per group); respective EC50 values were 6.2 and 6.8 nM. With dual simultaneous intracellular recording in endothelial tubes, current injection (±0.5 nA) into one EC evoked corresponding Vm responses (±5 mV) in a remote EC (separation distance, 500 μm), confirming electrical signal transmission along PA endothelium. These preliminary studies confirm that CGRP effectively hyperpolarizes SMCs and ECs in mouse PA while validating the utility of this model for investigating the nature of electrical signaling in response to sensory neurotransmission along the PA wall.Support or Funding InformationNIH R37‐HL041026