Role of protein sulfation in vasodilation induced by minoxidil sulfate, a K+ channel opener

• Published in: The Journal of pharmacology and experimental therapeutics Vol. 258; no. 3; pp. 1091 - 1097
• Main Authors: Meisheri, K D, Oleynek, J J, Puddington, L
• Format: Journal Article
• Language: English
• Published: United States American Society for Pharmacology and Experimental Therapeutics 01.09.1991
• Subjects: ANIMALS; ARTERIES; AZINES; BASIC BIOLOGICAL SCIENCES; BETA DECAY RADIOISOTOPES; BETA-MINUS DECAY RADIOISOTOPES; BIOCHEMICAL REACTION KINETICS; BLOOD VESSELS; BODY; CARDIOVASCULAR AGENTS; CARDIOVASCULAR SYSTEM; DAYS LIVING RADIOISOTOPES; DRUGS; ELECTROPHORESIS; EVEN-ODD NUCLEI; HETEROCYCLIC COMPOUNDS; HYDROGEN COMPOUNDS; ISOTOPE APPLICATIONS; ISOTOPES; KINETICS; LABELLING; LIGHT NUCLEI; MAMMALS; MEMBRANE PROTEINS; Membrane Proteins - metabolism; Minoxidil - analogs & derivatives; Minoxidil - pharmacology; MOLECULAR WEIGHT; Muscle Proteins - metabolism; Muscle Relaxation - drug effects; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Muscle, Smooth, Vascular - physiology; MUSCLES; NUCLEI; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORGANS; PHARMACOLOGY; Potassium Channels - drug effects; PROTEINS; PYRIMIDINES; Pyrimidines - pharmacology; RABBITS; RADIOISOTOPES; REACTION KINETICS; Space life sciences; SULFUR 35; SULFUR ISOTOPES; Sulfur Radioisotopes; TRACER TECHNIQUES; TRITIUM COMPOUNDS; VASODILATION; Vasodilator Agents - pharmacology; VASODILATORS; VERTEBRATES 550201 > Biochemistry > Tracer Techniques
• ISSN: 0022-3565; 1521-0103

Evidence from contractile, radioisotope ion flux and electrophysiological studies suggest that minoxidil sulfate (MNXS) acts as a K+ channel opener in vascular smooth muscle. This study was designed to examine possible biochemical mechanisms by which MNXS exerts such an effect. Experiments performed in the isolated rabbit mesenteric artery (RMA) showed that MNXS, 5 microM, but not the parent compound minoxidil, was a potent vasodilator. Whereas the relaxant effects of an another K+ channel opener vasodilator, BRL-34915 (cromakalim), were removed by washing with physiological saline solution, the effects of MNXS persisted after repeated washout attempts. Furthermore, after an initial exposure of segments of intact RMA to [35S] MNXS, greater than 30% of the radiolabel was retained 2 hr after removal of the drug. In contrast, retention of radiolabel was not detected with either [3H]MNXS (label on the piperidine ring of MNXS) or [3H]minoxidil (each less than 3% after a 2-hr washout). These data suggested that the sulfate moiety from MNXS was closely associated with the vascular tissue. To determine if proteins were the acceptors of sulfate from MNXS, intact RMAs were incubated with [35S]MNXS, and then 35S-labeled proteins were separated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and analyzed by fluorography. Preferential labeling of a 116 kD protein was detected by 2 and 5 min of treatment. A 43 kD protein (resembling actin) also showed significant labeling. A similar profile of 35S-labeled proteins was observed in [35S] MNXS-treated A7r5 rat aortic smooth muscle cells, suggesting that the majority of proteins labeled by [35S]MNXS in intact RMA were components of smooth muscle cells.