Effect of adrenomedullin on ion transport and muscle contraction in rat distal colon.
We have investigated the effects of adrenomedullin (AM) on mucosal ion transport using the Ussing method and smooth muscle contraction using the Magnus method in rat. Our results indicate that AM increases Isc (short-circuit current) for Cl- secretion (100 nM:170.0 +/- 41.2%, 1 microM:193.8 +/- 45.5%, 100% Isc:28.2 +/- 3.1 microA/cm2) with an initial small decrease of Isc, inhibiting Na+ absorption. Tetrodotoxin (TTX) inhibits the Isc response elicited by AM (86%). In addition, AM relaxes potassium-induced contraction (10 nM:11.1 +/- 8.51%, 100 nM:33.4 +/- 12.7%, 100% contraction: 1.8 +/- 0.22 g), and TTX inhibits the response elicited by AM (90%). We conclude that AM modulates water and ion transport as well as bowel movement, mainly through the colonic nervous system.
Department of Metabolism and Clinical Nutrition, Faculty of Medicine, Kyoto University, Japan. fukuda@metab.kuhp.kyoto-u.ac.jp
K
K
Fukuda
H
H
Tsukada
M
M
Onomura
T
T
Saito
M
M
Kodama
H
H
Nakamura
T
T
Taniguchi
M
M
Tominaga
M
M
Hosokawa
Y
Y
Seino
D053607:Adrenomedullin; D000818:Animals; D002712:Chlorides / Q000378:metabolism; D003106:Colon / Q000187:drug effects* / Q000378:metabolism; D007413:Intestinal Mucosa / Q000187:drug effects / Q000378:metabolism; D008297:Male; D009119:Muscle Contraction / Q000187:drug effects*; D010455:Peptides / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000378:metabolism; D013779:Tetrodotoxin / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
D002712:Chlorides; D010455:Peptides; D014665:Vasodilator Agents; D053607:Adrenomedullin; D013779:Tetrodotoxin; D012964:Sodium