Salvia miltiorrhiza causes tonic contraction in rat ileum through Ca²⁺-calmodulin pathway.
BACKGROUND
Danshen, root of Salvia miltiorrhiza (SM), has been traditionally used in Chinese medicine for the treatment of heart, abdomen, gurgling in the intestines, and relieving fullness. However, the effects of SM on intestine have rarely been done to date.


OBJECTIVE
To investigate the contraction effect of SM on isolated rat ileum and its mechanisms involved.


METHODS
The isometric contractions of ileum segments were investigated in organ baths for spontaneous activity and response to ethanolic extracts of SM. To determine the contraction mechanism caused by SM extracts, atropine (a muscarinic receptor antagonist), tetrodotoxin (TTX, a sodium channel blocker), nifedipine (a calcium channel blocker), Ca(2+) free Krebs solution with EGTA, or trifluoperazine (TFP, a calmodulin blocker) was administered and its response to cumulative dosages of SM extracts were examined. The effect of SM extracts on Ca(2+) signaling in the intestinal epithelial cell-6 (IEC-6) was examined using fura-2 as a Ca(2+) indicator.


RESULTS
SM extracts caused dose-dependent tonic contraction on rat ileum in ex vivo organ bath studies. The contraction induced by SM extracts was not inhibited by atropine, TTX, nifedipine, or in Ca(2+) free solution. However, the ileal contractions induced by SM extracts were significantly inhibited by TFP in a dose-dependent manner. In IEC-6 cells, the SM extracts induced extracellular Ca(2+) entry and massive intracellular Ca(2+) release in Ca(2+)-contained medium, and induced intracellular Ca(2+) release in Ca(2+)-free medium.


CONCLUSIONS
These results demonstrate that SM extracts cause ileal contraction through the Ca(2+)-calmodulin pathway.
Department of Pediatrics, E-Da Hospital/I-Shou University, No.1, Yida Road, Yanchao District, Kaohsiung, Taiwan.
Ching-Chung
CC
Tsai
Shih-Che
SC
Huang
Jong-Kang
JK
Liu
Hsiu-Chuan
HC
Wang
Tong-Rong
TR
Tsai
Ping-Ju
PJ
Tsai
Ching-Wen
CW
Liu
Li-Ching
LC
Chang
D045784:Abietanes / Q000032:analysis; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002118:Calcium / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000502:physiology*; D002460:Cell Line; D007082:Ileum / Q000187:drug effects* / Q000502:physiology; D066298:In Vitro Techniques; D008297:Male; D018727:Muscarinic Antagonists; D009119:Muscle Contraction / Q000187:drug effects; D009543:Nifedipine / Q000494:pharmacology; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D051381:Rats; D017207:Rats, Sprague-Dawley; D027561:Salvia miltiorrhiza; D026941:Sodium Channel Blockers / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology; D014268:Trifluoperazine / Q000494:pharmacology
D045784:Abietanes; D002121:Calcium Channel Blockers; D002147:Calmodulin; D018727:Muscarinic Antagonists; D010936:Plant Extracts; D026941:Sodium Channel Blockers; C021751:tanshinone; D014268:Trifluoperazine; D013779:Tetrodotoxin; D001285:Atropine; D009543:Nifedipine; D002118:Calcium