title: The mechano-gated channel inhibitor GsMTx4 reduces the exercise pressor reflex in rats with ligated femoral arteries.
abstract: Mechanical and metabolic stimuli arising from contracting muscles evoke the exercise pressor reflex. This reflex is greater in a rat model of simulated peripheral arterial disease in which a femoral artery is chronically ligated than it is in rats with freely perfused femoral arteries. The role played by the mechanically sensitive component of the exaggerated exercise pressor reflex in ligated rats is unknown. We tested the hypothesis that the mechano-gated channel inhibitor GsMTx4, a relatively selective inhibitor of mechano-gated Piezo channels, reduces the exercise pressor reflex in decerebrate rats with ligated femoral arteries. Injection of 10 μg of GsMTx4 into the arterial supply of the hindlimb reduced the pressor response to Achilles tendon stretch (a purely mechanical stimulus) but had no effect on the pressor responses to intra-arterial injection of α,β-methylene ATP or lactic acid (purely metabolic stimuli). Moreover, injection of 10 μg of GsMTx4 into the arterial supply of the hindlimb reduced both the integrated pressor area (control 535 ± 21, GsMTx4 218 ± 24 mmHg·s; P < 0.01), peak pressor (control 29 ± 2, GsMTx4 14 ± 3 mmHg; P < 0.01), and renal sympathetic nerve responses to electrically induced intermittent hindlimb muscle contraction (a mixed mechanical and metabolic stimulus). The reduction of the integrated pressor area during contraction caused by GsMTx4 was greater in rats with ligated femoral arteries than it was in rats with freely perfused femoral arteries. We conclude that the mechanically sensitive component of the reflex contributes to the exaggerated exercise pressor reflex during intermittent hindlimb muscle contractions in rats with ligated femoral arteries.
authors.affiliation: Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania; and.
authors.forename: Steven W
authors.initials: SW
authors.lastname: Copp
authors.affiliation: Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania; and.
authors.forename: Joyce S
authors.initials: JS
authors.lastname: Kim
authors.affiliation: Department of Anesthesiology, Penn State College of Medicine, Hershey, Pennsylvania.
authors.forename: Victor
authors.initials: V
authors.lastname: Ruiz-Velasco
authors.affiliation: Heart and Vascular Institute, Penn State College of Medicine, Hershey, Pennsylvania; and mkaufman@hmc.psu.edu.
authors.forename: Marc P
authors.initials: MP
authors.lastname: Kaufman
mesh_terms: D000125:Achilles Tendon / Q000294:innervation; D000818:Animals; D002628:Chemoreceptor Cells / Q000378:metabolism; D003655:Decerebrate State; D004195:Disease Models, Animal; D004558:Electric Stimulation; D005263:Femoral Artery / Q000601:surgery*; D006614:Hindlimb; D007269:Injections, Intra-Arterial; D036341:Intercellular Signaling Peptides and Proteins; D007473:Ion Channels / Q000037:antagonists & inhibitors* / Q000378:metabolism; D008026:Ligation; D008297:Male; D040542:Mechanotransduction, Cellular / Q000187:drug effects*; D049990:Membrane Transport Modulators / Q000008:administration & dosage / Q000494:pharmacology*; D009119:Muscle Contraction; D018482:Muscle, Skeletal / Q000294:innervation* / Q000378:metabolism*; D010455:Peptides / Q000008:administration & dosage / Q000494:pharmacology*; D058729:Peripheral Arterial Disease / Q000503:physiopathology*; D017207:Rats, Sprague-Dawley; D012026:Reflex, Stretch / Q000187:drug effects*; D013111:Spider Venoms / Q000008:administration & dosage / Q000494:pharmacology*; D013564:Sympathetic Nervous System / Q000187:drug effects / Q000378:metabolism / Q000503:physiopathology; D013997:Time Factors
chemical_list: D036341:Intercellular Signaling Peptides and Proteins; D007473:Ion Channels; C411249:MTx4 protein, Grammostola spatulata; D049990:Membrane Transport Modulators; D010455:Peptides; D013111:Spider Venoms
keywords: Piezo channels; mechanoreceptors; sympathetic nerve activity; thin-fiber muscle afferents