Endothelium-derived factors and k+ channels are involved in the vasorelaxation induced by Sida cordifolia L. in the rat superior mesenteric artery.
The vasorelaxantion of the aqueous fraction of the hydroalcoholic extract of the Sida cordifolia leaves (AFSC) was evaluated in this work. In rat superior mesenteric artery, AFSC (3-1000 microg/mL) induced relaxation of phenylephrine-induced contractions. This effect was significantly attenuated after removal of the endothelium, after atropine (1 microM), L-NAME (100 microM), indomethacin (10 microM), high K+ (20 mM), tetraethylammonium (1 microM), a K(Ca) blocker, apamin (1 microM), a SK(Ca) blocker and ChTX (0.1 microM), a BK(Ca) blocker, however, it was not affected after glibenclamide (10 microM), an KATP blocker, and 4-aminopyridine (1 microM), a Kv blocker. ChTX (0.1 microM) was able to induce an additional inhibition of the vasorelaxation induced by AFSC in the presence of L-NAME plus indomethacin. The vasorelaxation induced by AFSC in the presence of L-NAME plus indomethacin plus ChTX was not different from that induced by AFSC in rings without endothelium. In conclusion, the results show that endothelium-derived factors (mainly NO, PGI2) and K+ channels (BK(Ca) and SK(Ca)) play a crucial role in the vasorelaxation induced by AFSC in the rat superior mesenteric artery.
Santos
M R V
MR
Universidade Federal de Sergipe, Departamento de Fisiologia, São Cristóvão, SE, Brazil.
Nascimento
N M S
NM
Antoniolli
A R
AR
Medeiros
I A
IA
D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000494:pharmacology; D018999:Charybdotoxin / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000187:drug effects / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D019660:Malvaceae / Q000737:chemistry*; D017538:Mesenteric Artery, Superior / Q000187:drug effects / Q000502:physiology*; D009126:Muscle Relaxation / Q000187:drug effects / Q000502:physiology; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D052250:Nitric Oxide Synthase Type III / Q000037:antagonists & inhibitors; D010936:Plant Extracts / Q000494:pharmacology; D018515:Plant Leaves / Q000737:chemistry; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D011189:Potassium Chloride / Q000494:pharmacology; D051381:Rats
D000894:Anti-Inflammatory Agents, Non-Steroidal; D004791:Enzyme Inhibitors; D010936:Plant Extracts; D015221:Potassium Channels; D018999:Charybdotoxin; D011189:Potassium Chloride; D052250:Nitric Oxide Synthase Type III; D019331:NG-Nitroarginine Methyl Ester; D007213:Indomethacin