title: Hydrogen sulfide as an endogenous modulator of biliary bicarbonate excretion in the rat liver.
abstract: Cystathionine gamma-lyase (CSE) is an enzyme catalyzing cystathionine and cysteine to yield cysteine and hydrogen sulfide (H(2)S), respectively. This study aimed to examine if H(2)S generated from the enzyme could serve as an endogenous regulator of hepatobiliary function. Gas chromatographic analyses indicated that, among rat organs herein examined, liver constituted one of the greatest components of H(2)S generation in the body, at 100 mumol/g of tissue, comparable to that in kidney and 1.5-fold greater than that in brain, where roles of the gas in the regulation of neurotransmission were reported previously. At least half of the gas amount in the liver appeared to be derived from CSE, because blockade of the enzyme by propargylglycine suppressed it by 50%. Immunohistochemistry revealed that CSE occurs not only in hepatocytes, but also in bile duct. In livers in vivo, as well as in those perfused ex vivo, treatment with the CSE inhibitor induced choleresis by stimulating the basal excretion of bicarbonate in bile samples. Transportal supplementation of NaHS at 30 mumol/L, but not that of N-acetylcysteine as a cysteine donor, abolished these changes elicited by the CSE inhibitor in the perfused liver. The changes elicited by the CSE blockade did not coincide with alterations in hepatic vascular resistance, showing little involvement of vasodilatory effects of the gas in these events, if any. These results first provided evidence that H(2)S generated through CSE modulates biliary bicarbonate excretion and is thus a determinant of bile salt-independent bile formation in the rat liver.
authors.affiliation: Division of Surgical Oncology, Department of Surgery, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Kimihito
authors.initials: K
authors.lastname: Fujii
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Sakuragawa
authors.forename: Misato
authors.initials: M
authors.lastname: Kashiba
authors.forename: Yasoo
authors.initials: Y
authors.lastname: Sugiura
authors.forename: Mieko
authors.initials: M
authors.lastname: Kondo
authors.forename: Kayo
authors.initials: K
authors.lastname: Maruyama
authors.forename: Nobuhito
authors.initials: N
authors.lastname: Goda
authors.forename: Yuji
authors.initials: Y
authors.lastname: Nimura
authors.forename: Makoto
authors.initials: M
authors.lastname: Suematsu
mesh_terms: D000480:Alkynes / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001639:Bicarbonates / Q000378:metabolism*; D001646:Bile / Q000378:metabolism*; D001647:Bile Acids and Salts / Q000378:metabolism; D003542:Cystathionine gamma-Lyase / Q000037:antagonists & inhibitors / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005998:Glycine / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000494:pharmacology; D006862:Hydrogen Sulfide / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D010477:Perfusion; D051381:Rats; D017208:Rats, Wistar; D013440:Sulfides / Q000494:pharmacology
chemical_list: D000480:Alkynes; D001639:Bicarbonates; D001647:Bile Acids and Salts; D004791:Enzyme Inhibitors; D013440:Sulfides; C009055:propargylglycine; D003542:Cystathionine gamma-Lyase; C025451:sodium bisulfide; D005998:Glycine; D006862:Hydrogen Sulfide