Involvement of sensory nerves in vasodilator responses to acetylcholine and potassium ions in rat hepatic artery

• In the presence of ouabain (1 mM), acetylcholine and KCl (5 mM) evoked endothelium-independent relaxations in rat hepatic arteries. Treatment with capsaicin (10 μM), scopolamine (1 μM) or CGRP8-37 (3 μM) prevented these relaxations. Acetylcholine-induced relaxations in intact arterial segments in the presence of indomethacin (10 μM) and N(G)-nitro-L-arginine (0.3 mM) were only partially inhibited by ouabain plus BaCl2 (30 μM). However, ouabain plus BaCl2 almost abolished such relaxations in capsaicin-pre-treated preparations. In arteries without endothelium, the neurosecretagogue α-latrotoxin (1 nM) induced complete relaxations, which were abolished by CGRP8-37 or pre-treatment with capsaicin. α-Latrotoxin also induced a smooth muscle hyperpolarization (12 ± 2 mV), which was abolished by CGRP8-37. The ability of ouabain to disclose a CGRP-mediated neurogenic relaxation must be considered when this agent is used as a pharmacological tool. The results further suggest that CGRP is a nerve-derived hyperpolarizing factor in the rat hepatic artery.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinska och farmaceutiska grundvetenskaper -- Farmakologi och toxikologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Basic Medicine -- Pharmacology and Toxicology (hsv//eng)

Nyckelord

Endothelium-derived hyperpolarizing factor

Endothelium-derived relaxing factors

Hyperpolarization

Membrane potential

Nitric oxide

Potassium channels

Vascular endothelium

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art (ämneskategori)

ref (ämneskategori)