In this study the investigators will investigate the acute effects of increasing alanine exposure on metabolic parameters in healthy participants. Participants will participate in one study day. After initial baseline blood samples, a three-hour intravenous infusion with glucagon will be initiated. The infusion rate will be increased every 30 minutes.
Two peripheral catheters will be placed in the antecubital vein of each arm for infusion of L-alanine and blood sampling respectively. The infusion rate of alanine will start at 1.4 μmol/kg/min and increase every 30 minutes over a 3-hour period, up to a maximum of 28 μmol/kg/min. The study day will last approximately 4 hours, and a maximal blood volume of 130 ml will be collected. Blood samples for the analysis of plasma glucagon, glucose, insulin, C-peptide etc. will be drawn every 15 minutes.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
BASIC_SCIENCE
Masking
NONE
Enrollment
15
A three-hour intravenous infusion with alanine with increasing infusion rate (from 1.4 μmol/kg/min and to 28 μmol/kg/min)
Department of Clinical Biochemistry, Copenhagen University Hospital - Bispebjerg and Frederiksberg
Copenhagen, Denmark
Threshold alanine infusion rate for stimulation of plasma glucagon
Lowest alanine infusion rate (µmol/kg/min) at which plasma glucagon concentration is significantly higher than baseline during a 3-hour stepwise alanine infusion (six 30-minute steps from 1.4 to 28 µmol/kg/min).
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Change in plasma glucose during stepwise alanine infusion
Plasma glucose concentration (mmol/L) measured at baseline and every 30 minutes during a 3-hour stepwise alanine infusion (1.4-28 µmol/kg/min), analyzed as absolute values and change from baseline.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Change in plasma follicle-stimulating hormone (FSH) during stepwise alanine infusion
Plasma follicle-stimulating hormone (FSH) concentration (IU/L) measured at baseline and at the end of the 3-hour stepwise alanine infusion to explore acute effects on pituitary gonadotropin secretion.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Change in plasma luteinizing hormone (LH) during stepwise alanine infusion
Plasma luteinizing hormone (LH) concentration (IU/L) measured at baseline and at the end of the 3-hour stepwise alanine infusion to explore acute effects on pituitary gonadotropin secretion.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Change in plasma cortisol during stepwise alanine infusion
Plasma cortisol concentration (nmol/L) measured at baseline and every 60 minutes during the 3-hour stepwise alanine infusion to assess activation of the hypothalamic-pituitary-adrenal axis.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Elvar Már Sturlaugsson Jóhönnuson, Stud. Med.
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Change in plasma triglycerides during stepwise alanine infusion
Plasma triglyceride concentration (mmol/L) measured at baseline and at the end of the 3-hour stepwise alanine infusion to evaluate acute effects on lipid metabolism.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Change in plasma urea during stepwise alanine infusion
Plasma urea (carbamide) concentration (mmol/L) measured at baseline and at the end of the 3-hour stepwise alanine infusion to assess short-term effects on nitrogen metabolism.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Change in plasma alanine aminotransferase (ALAT) during stepwise alanine infusion
Plasma alanine aminotransferase (ALAT/ALT) activity (U/L) measured at baseline and at the end of the 3-hour stepwise alanine infusion to assess acute changes in liver enzyme levels.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Change in plasma C-peptide during stepwise alanine infusion
Plasma C-peptide concentration (pmol/L) measured at baseline and every 30 minutes during a 3-hour stepwise alanine infusion, analyzed as absolute values and change from baseline.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.
Change in plasma insulin during stepwise alanine infusion
Plasma insulin concentration (pmol/L) measured at baseline and every 30 minutes during a 3-hour stepwise alanine infusion, analyzed as absolute values and change from baseline.
Time frame: Baseline and every 30 minutes during the 0-180 min infusion period.