[THE ROLE OF HYDROGEN SULFIDE IN REGULATION OF CIRCULATION BLOOD LIVER]

Area of Science:

• Physiology
• Biochemistry
• Pharmacology

Context:

• Hydrogen sulfide (H2S) is increasingly recognized for its physiological roles.
• Understanding H2S regulation in hepatic circulation is crucial for cardiovascular health.
• The role of L-cysteine as an H2S precursor and its impact on liver hemodynamics requires further elucidation.

Purpose:

• To investigate the effects of exogenous hydrogen sulfide administration on intrahepatic blood flow and systemic blood pressure in rats.
• To determine the role of the enzyme cystathionine-gamma-lyase in mediating the vascular effects of L-cysteine in the liver.
• To explore the impact of inhibiting endogenous H2S synthesis on hepatic hemodynamics.

Summary:

• Intraportal administration of L-cysteine or the hydrogen sulfide donor NaHS in rats led to significant decreases in systemic blood pressure (SBP) and portal vein pressure (PVP), alongside increases in liver blood flow (LF) and blood filling (BF).
• Blocking cystathionine-gamma-lyase with DL-propargylglycine abolished the vasodilatory effects of L-cysteine and inhibited endogenous H2S synthesis, resulting in increased SBP and PVP, and decreased BF and LF.
• These findings indicate that hydrogen sulfide plays a key role in regulating intrahepatic vascular tone and blood pressure.

Impact:

• This study highlights the vasodilatory properties of hydrogen sulfide in the liver, suggesting therapeutic potential for conditions involving hepatic vasoconstriction.
• The results underscore the importance of the H2S-synthesizing enzyme cystathionine-gamma-lyase in maintaining hepatic vascular homeostasis.
• Understanding these mechanisms could lead to novel strategies for managing liver diseases and circulatory disorders.