[Effects of two metabolites of cultured marine fungus, Halorosellinia oceanicum 323, on the contraction of isolated guinea-pig ileum].
OBJECTIVE
To investigate the effects of 323-A and 323-B, two isomers extracted from the metabolites of cultured marine fungus, Halorosellinia oceanicum 323, on the contraction of isolated guinea pig ileum (GPI).


METHODS
The GPI contractions were recorded with a two-channel-physiological recorder with tension transducers. Cumulative dose-response curves of contractions of isolated GPI induced by histamine (Hist), acetylcholine (ACh) and potassium chloride (KCl) were constructed, then the influences of 323-A and 323-B on each curve were observed. Furthermore, possible mechanisms underlying effects of the two compounds were explored by analyzing their influences on the biphasic contractile response to ACh, with comparison of a calcium antagonist, verapamil (Ver).


RESULTS
The data indicated that both 323-A and 323-B inhibited the contractile actions of GPI triggered by Hist, ACh and KCl in a concentration-dependent manner, with pD2' values of 5.13, 4.97, 5.36 and 5.51, 5.56, 5.62, respectively. The initial phase component of the ACh-elicited contractions, in the absence of external Ca2+, was significantly reduced by 323-A, 323-B, as well as Ver, whereas the subsequent sustained tonic contractions induced by adding Ca2+ to the bath solution were almost unaffected.


CONCLUSIONS
These results suggest that 323-A and 323-B have calcium antagonistic effects similar to that of Ver in mechanisms, and they might have potential to be developed as calcium antagonists.
Luo
Jing-hui
JH
Pharmaceutical Department, Nanfang Hospital, Guangzhou 510515, China.
Yang
Ying-bao
YB
Lin
Yong-cheng
YC
Jiang
Guang-ce
GC
Chen
Zhi-liang
ZL
D000109:Acetylcholine / Q000037:antagonists & inhibitors; D000818:Animals; D002118:Calcium / Q000037:antagonists & inhibitors; D002121:Calcium Channel Blockers / Q000302:isolation & purification / Q000494:pharmacology*; D005260:Female; D005658:Fungi / Q000737:chemistry*; D006168:Guinea Pigs; D006633:Histamine Antagonists / Q000494:pharmacology; D007082:Ileum / Q000187:drug effects / Q000502:physiology; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D009130:Muscle, Smooth / Q000187:drug effects*; D011189:Potassium Chloride / Q000037:antagonists & inhibitors
D002121:Calcium Channel Blockers; D006633:Histamine Antagonists; D011189:Potassium Chloride; D000109:Acetylcholine; D002118:Calcium