Effect of verapamil on glycogenolysis and gluconeogenesis in the perfused rat liver

✍ Scribed by Badr, Mostafa

• Publisher: John Wiley and Sons
• Year: 1989
• Tongue: English
• Weight: 303 KB
• Volume: 4
• Category: Article
• ISSN: 0887-2082
• DOI: 10.1002/jbt.2570040107

✦ Synopsis

In perfused livers from fed rats, rates of glucose production (glycogenolysis) were 133 f 12 pmollglhr. Infusion of 2 pM verapamil into these livers decreased the rates of glucose production significantly to 97 * 15 pmollglhr within 10 min. Conversely, rates of production of lactate plus pyruvate (glycolysis) of 64 k 6 pmollglhr were not significantly altered by verapamil(60 f 3 pmollglhr). When 50 pM verapamil was infused, however, rates of both glycogenolysis and glycolysis were diminished to 56 f 11 and 43 f 5 pmollglhr, respectively. In perfused livers from fasted rats, infusion of 20 mM fructose increased the rates of production of glucose (gluconeogenesis) significantly from 11 f 7 to 121 f 17 pmollglhr. These rates reached 138 f 7 pmollglhr upon the simultaneous infusion of verapamil (2 pM). In these livers, fructose also increased rates of production of lactate from 6 f 2 to 132 f 11 pmollglhr, which were further increased to 143 f 8 pmollglhr when 2 pM verapamil was infused. The results show that calcium-dependent processes involved in hepatic carbohydrate metabolism respond differently to the calcium channel blocker verapamil. Low concentrations of verapamil inhibited glycogenolysis significantly while having no effect on either glycolysis or gluconeogenesis. These data suggest that these two processes have different sensitivities to changes in intracellular calcium concentrations andlor different sources of regulatory calcium.