Effect of capsaicin on membrane currents in cultured vascular smooth muscle cells of rat aorta |
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| Affiliation: | 1. Department of Pharmacology, Kaohsiung Medical College, Kaohsiung, Taiwan;2. Department of Physiology, Kaohsiung Medical College, Kaohsiung, Taiwan;3. Department of Pediatrics, Kaohsiung Medical College, Kaohsiung, Taiwan;1. Boston University School of Medicine, 72 East Concord St, Boston, MA, 02118, United States;2. Department of Surgery, Division of Thoracic Surgery, United States;3. Boston University School of Medicine, Department of Pathology, United States;1. Food and Nutritional Sciences Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong;2. Molecular Biotechnology Programme, School of Life Sciences, Faculty of Science, The Chinese University of Hong Kong, Shatin, N.T., Hong Kong;3. Department of Food Science, National Chiayi University, Chiayi City, Taiwan;1. Department of Anatomic Pathology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan;2. Department of Orthopaedic Surgery, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan;1. The State Key Laboratory Breeding Base of Basic Science of Stomatology (Hubei-MOST) and Key Laboratory of Oral Biomedicine Ministry of Education, School and Hospital of Stomatology, Wuhan University, Wuhan, China;2. Department of Oral Maxillofacial–Head Neck Oncology, School and Hospital of Stomatology, Wuhan University, Wuhan, China;3. Department of Pathology, School and Hospital of Stomatology, Wuhan University, Wuhan, China;1. Department of Urology, Mayo Clinic, Rochester, Minnesota;2. Department of Pathology, Mayo Clinic, Rochester, Minnesota;3. Department of Health Sciences Research, Mayo Clinic, Rochester, Minnesota |
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| Abstract: | The application of capsaicin (1 μM) produced a minor relaxant effect in endothelium-denuded rat aortae. However, capsaicin caused a greater relaxation of blood vessels precontracted with high K+ or phenylephrine. The effects of capsaicin on the ionic currents were also examined in A7r5 vascular smooth muscle cells. The tight-seal whole-cell voltage clamp technique was used. Capsaicin inhibited the Ba2+ inward current (IBa) through the voltage-dependent L-type Ca2+ channel in a concentration-dependent fashion, whereas calcitonin gene-related peptide and phenylephrine produced a minor increase in IBa. Capsaicin did not alter the overall shape of current-voltage relationship of IBa. However, capsaicin (3 μM) shifted the quasi-steady-state inactivation curve of IBa to more negative membrane potential by about 5 mV. These effects of capsaicin on IBa were reversible. In addition, capsaicin had inhibitory effects on voltage dependent K+ currents. These results suggest that inhibition of the voltage-dependent L-type Ca2+ channel is involved in the capsaicin-induced relaxation of the vascular smooth muscle, whereas capsaicin-induced inhibition of voltage-dependent K+ channels might produced an increase in cell excitability. |
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