L-type Calcium Channel Blockade Worsens Glucose Tolerance and β-Cell Function in C57BL6/J Mice Exposed to...

Area of Science:

• Endocrinology
• Cardiovascular Pharmacology
• Sleep Medicine

Background:

• Obstructive sleep apnea (OSA) causes intermittent hypoxemia (IH), negatively impacting glucose homeostasis.
• Nifedipine, an L-type calcium channel blocker for hypertension, can also affect insulin sensitivity and secretion.
• The combined effects of IH and nifedipine on glucose metabolism remain uninvestigated.

Purpose of the Study:

• To investigate the cumulative and interactive effects of intermittent hypoxemia (IH) and nifedipine on glucose homeostasis in mice.

Main Methods:

• Adult male C57BL6/J mice were exposed to IH or intermittent air (IA) for five days.
• Mice received either nifedipine (20 mg/kg/day) or vehicle via osmotic pumps.
• Four groups were established: IA-vehicle, IA-nifedipine, IH-vehicle, and IH-nifedipine.

Main Results:

• IH significantly increased fasting glucose and insulin levels compared to controls.
• Nifedipine alone worsened glucose tolerance, and IH exacerbated this impairment.
• Nifedipine reduced glucose-stimulated insulin secretion and the insulinogenic index, effects further worsened by IH.

Conclusions:

• Intermittent hypoxemia detrimentally impacts insulin sensitivity and glucose tolerance.
• Nifedipine exacerbates these disturbances by impairing pancreatic beta-cell function.
• Caution is advised when prescribing L-type calcium channel blockers to OSA patients, especially those at risk for type 2 diabetes.