title: Rock Tea extract (Jasonia glutinosa) relaxes rat aortic smooth muscle by inhibition of L-type Ca(2+) channels.
abstract: In traditional herbal medicine, Rock Tea (Jasonia glutinosa) is known for its prophylactic and therapeutic value in various disorders including arterial hypertension. However, the mechanism by which Rock Tea exerts blood pressure-lowering actions has not been elucidated yet. Our aim was to demonstrate vasorelaxing effects of Rock Tea extract and to reveal its possible action mechanism. Isometric myography was conducted on high-K+-precontracted rings from rat thoracic aorta and tested extracts at concentrations of 0.5-5 mg/ml. Whole-cell patch-clamp experiments were performed in rat aortic vascular smooth muscle cells (line A7r5) to determine blocking effects on L-type Ca(2+) channels. Rock Tea extract relaxed the aorta contracted by high [K+] concentration dependently with an EC50 of ≈2.4 mg/ml and produced ≈75 % relaxation at the highest concentration tested. The L-type Ca(2+) channel blocker, verapamil (10(-6) M), had similar effects. Rock Tea extract had no effect in nominally Ca(2+)-free high-K(+) buffer but significantly inhibited contractions to re-addition of Ca(2+). Rock Tea extract inhibited the contractions induced by the L-type Ca(2+) channel activator Bay K 8644 (10(-5) M) and by phenylephrine (10(-6) M). Rock Tea extract and Y-27632 (10(-6) M), Rho-kinase inhibitor, had similar effects and the respective effects were not additive. Patch-clamp experiments demonstrated that Rock Tea extract (2.5 mg/ml) virtually abolished L-type Ca(2+) currents in A7r5. We conclude that Rock Tea extract produced vasorelaxation of rat aorta and that this relaxant effect is mediated by inhibition of L-type Ca(2+) channels. Rock Tea extracts may be of phytomedicinal value for prevention and adjuvant treatment of hypertension and other cardiovascular diseases.
authors.forename: Marta Sofía
authors.initials: MS
authors.lastname: Valero
authors.forename: Aida
authors.initials: A
authors.lastname: Oliván-Viguera
authors.forename: Irene
authors.initials: I
authors.lastname: Garrido
authors.forename: Elisa
authors.initials: E
authors.lastname: Langa
authors.forename: César
authors.initials: C
authors.lastname: Berzosa
authors.forename: Víctor
authors.initials: V
authors.lastname: López
authors.forename: Carlota
authors.initials: C
authors.lastname: Gómez-Rincón
authors.forename: María Divina
authors.initials: MD
authors.lastname: Murillo
authors.forename: Ralf
authors.initials: R
authors.lastname: Köhler
mesh_terms: D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology*; D001011:Aorta / Q000187:drug effects / Q000503:physiopathology; D019659:Asteraceae / Q000737:chemistry; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D020746:Calcium Channels, L-Type / Q000378:metabolism; D020013:Calcium Signaling; D004353:Drug Evaluation, Preclinical; D008297:Male; D009126:Muscle Relaxation; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000503:physiopathology; D018408:Patch-Clamp Techniques; D010656:Phenylephrine / Q000494:pharmacology; D010936:Plant Extracts / Q000494:pharmacology*; D017208:Rats, Wistar; D000069459:Teas, Herbal; D014664:Vasodilation; D014665:Vasodilator Agents / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology
chemical_list: D000959:Antihypertensive Agents; D002121:Calcium Channel Blockers; D020746:Calcium Channels, L-Type; D010936:Plant Extracts; D000069459:Teas, Herbal; D014665:Vasodilator Agents; D010656:Phenylephrine; D014700:Verapamil