Differential hyperpolarization to substance P and calcitonin gene‐related peptide in smooth muscle versus endothelium of mouse mesenteric artery

Abstract

Objective We sought to define how sensory neurotransmitters substance P and calcitonin gene‐related peptide (CGRP) affect membrane potential of vascular smooth muscle and endothelium. Methods Microelectrodes recorded membrane potential of smooth muscle from pressurized mouse mesenteric arteries (diameter, ~150 µm) and in endothelial tubes. Results Resting potential was similar (~ −45 mV) for each cell layer. Substance P hyperpolarized smooth muscle and endothelium ~ −15 mV; smooth muscle hyperpolarization was abolished by endothelial disruption or NO synthase inhibition. Blocking KCa channels (apamin + charybdotoxin) attenuated hyperpolarization in both cell types. CGRP hyperpolarized endothelium and smooth muscle ~ −30 mV; smooth muscle hyperpolarization was independent of endothelium. Blocking KCa channels prevented hyperpolarization to CGRP in endothelium but not smooth muscle. Inhibiting KATP channels with glibenclamide or genetic deletion of KIR6.1 attenuated hyperpolarization in smooth muscle but not endothelium. Pinacidil (KATP channel agonist) hyperpolarized smooth muscle more than endothelium (~ −35 vs. ~ −20 mV). Conclusions Calcitonin gene‐related peptide elicits greater hyperpolarization than substance P. Substance P hyperpolarizes both cell layers through KCa channels and involves endothelium‐derived NO in smooth muscle. Endothelial hyperpolarization to CGRP requires KCa channels, while KATP channels mediate hyperpolarization in smooth muscle. Differential K+ channel activation in smooth muscle and endothelium through sensory neurotransmission may selectively tune mesenteric blood flow.

Dural Immune Cells, CGRP, and Migraine

“…The trigeminal afferents also release small molecules such as glutamate ( 63 ). CGRP directly binds to vascular smooth muscle cells and causes hyperpolarization through metabotropic signaling and downstream phosphorylation of K ATP channels by protein kinase A ( 64 ). This results in relaxation and thus vasodilation.…”

Adventitial macrophage accumulation impairs perivascular nerve function in mesenteric arteries with inflammatory bowel disease

“…L-NAME also had no effect on sensory vasodilation in Control or IBD mice after macrophage depletion ( Figures 6B, D ), suggesting that nitric oxide generation is not an important target for restoring sensory vasodilation in this model. Because CGRP and SP can also elicit vasodilation via endothelium dependent hyperpolarization in these arteries ( Norton et al, 2021b ), additional experiments exploring these mechanisms would be required to fully define how IBD affects endothelial effects of CGRP and SP.…”

Role of Sensory Nerves in Pulmonary Fibrosis

“…Substance P is synthesized in cell bodies within the dorsal root ganglia and transported in vesicles, along with CGRP and ATP, via axons to sensory nerve terminals [ 28 , 45 ]. Following its release, substance P elicits its effect by binding to neurokinin-1 receptors (NK1Rs) coupled to G-protein signaling in airways [ 46 ] and in vascular ECs [ 28 , 47 ]. Substance P does not undergo reuptake and, therefore, continues exerting its effects until undergoing enzymatic degradation [ 45 ].…”

“…Substance P does not undergo reuptake and, therefore, continues exerting its effects until undergoing enzymatic degradation [ 45 ]. Its vascular effects include hyperpolarization and increases in [Ca 2+ ] i in ECs, which activate endothelial nitric oxide synthase (eNOS) [ 47 , 48 ]. This causes hyperpolarization and vasorelaxation in SMCs.…”

“…This causes hyperpolarization and vasorelaxation in SMCs. The dependency of this response on endothelial nitric oxide signaling is demonstrated by the loss of SMC hyperpolarization when the endothelium is disrupted or when eNOS is inhibited in isolated mesenteric arteries [ 47 ].…”