| In vivo: |
| Diabetes Care. 1997 Sep;20(9):1430-4. | | Glibenclamide, but not acarbose, increases leptin concentrations parallel to changes in insulin in subjects with NIDDM.[Pubmed: 9283792] | To hypothesize if glibenclamide, which increases insulin levels, also increases leptin concentrations.
METHODS AND RESULTS:
Leptin is a hormone that regulates weight in mice. In obese humans, leptin concentrations are increased, suggesting resistance to the effects of this hormone. Although short-term infusion of insulin during the hyperinsulinemiceuglycemic clamp does not increase leptin concentration, the effect of oral antidiabetic agents on leptin concentration is unknown. Differing effects can be expected, since glibenclamide acts via stimulation of insulin secretion, whereas acarbose inhibits alpha-glucosidases of the small intestine and has no direct effect on insulin levels. We examined the effect of acarbose (n = 4), glibenclamide (n = 6), and placebo (n = 6) on insulin and leptin levels during 24-h periods before and after 16 weeks of therapy.
We observed a significant diurnal variation in leptin concentrations. This was inversely related to insulin levels during the 24-h follow-up with usual diet. Neither the placebo nor acarbose altered leptin concentrations. However, glibenclamide increased leptin concentrations parallel to insulin levels. There were only minor changes in body weight during the l6-week follow-up: decrease in the placebo group (change -0.5 kg/m2, P = 0.07) and acarbose (change -0.7 kg/m2, P = 0.046) and increase in the glibenclamide group (change 0.8 kg/m2, P = 0.27). However, individual subjects who gained weight had increases in their leptin concentrations. The diurnal variation in leptin concentrations was preserved after glibenclamide.
CONCLUSIONS:
Glibenclamide increases circadian leptin and insulin concentrations, whereas acarbose does not. This observation may help to explain weight gain in subjects treated with glibenclamide and stable weight in those treated with acarbose in the long run. | | Br J Pharmacol. 1989 May;97(1):57-64. | | Inhibition by glibenclamide of the vasorelaxant action of cromakalim in the rat.[Pubmed: 2497925] |
METHODS AND RESULTS:
1. In rat isolated thoracic aortic rings pre-contracted with noradrenaline (10(-6) M), cromakalim (3 x 10(-7)-3 x 10(-5) M) produced concentration-related relaxation. This effect was progressively inhibited by increasing concentrations of the anti-diabetic sulphonylurea drug, glibenclamide (10(-6)-10(-5) M). 2. In rat isolated portal veins, cromakalim (3 x 10(-8)-10(-6) M) produced concentration-related inhibition of the spontaneous contractive activity and glibenclamide (3 x 10(-7)-3 x 10(-6) M) prevented this inhibitory action in a concentration-dependent manner. 3. In both rat aortic rings and portal veins, cromakalim (10(-5) M) stimulated 86Rb efflux. Prior exposure to glibenclamide (10(-7)-10(-6) M) produced a concentration-related inhibition of this response. 4. In conscious rats, cromakalim, 0.075 mg kg-1 i.v., produced a rapid and sustained fall in arterial blood pressure which was not influenced by pretreatment (2 h) with a large oral dose of glibenclamide (100 mg kg-1). 5. In conscious rats, the hypotensive action of cromakalim, 0.075 mg kg-1 i.v., was abolished by pretreatment (30 min) with glibenclamide, 20 mg kg-1, given by the intravenous route.
CONCLUSIONS:
6. The results suggest that the vasorelaxant and hypotensive actions of cromakalim involve a K+ channel which can be inhibited by glibenclamide, but which may be distinct from the ATP-sensitive K+ channel of the pancreatic beta-cell. | | Endocrinology. 2018 Jul 1;159(7):2614-2620. | | Glibenclamide Prevents Hypoglycemia-Induced Fatal Cardiac Arrhythmias in Rats.[Pubmed: 29800118 ] | Sulfonylureas increase the incidence of severe hypoglycemia in people with type 2 diabetes and might increase the risk of sudden cardiac death. Sulfonylureas stimulate insulin secretion by closing pancreatic ATP-sensitive potassium ion (KATP) channels.
METHODS AND RESULTS:
To investigate the role of KATP channel modulators on cardiac arrhythmias and mortality in the setting of severe hypoglycemia, adult Sprague-Dawley rats underwent hyperinsulinemic (0.2 U/kg/min) severe hypoglycemic (10 to 15 mg/dL) clamps with continuous electrocardiography. The rats were randomized for treatment with intravenous vehicle (VEH), the sulfonylurea glibenclamide (GLIB; KATP channel blocker; 5 mg/kg/h), or diazoxide (DIAZ; KATP channel opener; 5 mg/kg/h). The results demonstrated that GLIB completely prevented first-degree heart block compared with VEH (0.18 ± 0.09/min) and DIAZ (0.2 ± 0.05/min). Second-degree heart block was significantly reduced with GLIB (0.12 ± 0.1/min) compared with VEH (0.6 ± 0.2/min) and DIAZ (6.9 ± 3/min). The incidence of third-degree heart block was completely prevented by GLIB compared with VEH (67%) and DIAZ (87.5%). Hypoglycemia-induced mortality was completely prevented by GLIB compared with VEH (60%) and DIAZ (82%).
CONCLUSIONS:
In conclusion, although GLIB increases the risk of hypoglycemia by increasing insulin secretion, these results have demonstrated a paradoxical protective role of GLIB against severe hypoglycemia-induced fatal cardiac arrhythmias. |
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