Lactate is essential for maintenance of euglycemia in iron-deficient rats at rest and during exercise.
To evaluate the hypothesis that lactate supply is essential to maintain euglycemia during iron deficiency, female Sprague-Dawley rats were assigned to iron-sufficient (50 mg Fe2+/kg diet, +Fe), or iron-deficient (15 mg Fe2+/kg diet, -Fe) dietary groups and were injected with a specific beta 2-adrenergic inhibitor, ICI 118,551 (1.0 mg/kg body wt). Rats were studied at rest or after 30 min of running at 13.4 m/min 0% grade. Dietary iron deficiency decreased hemoglobin concentration 38%, but resting arterial concentrations of glucose ([Glc]), lactate ([La]), or alanine ([Ala]) were unaffected. Administration of ICI 118,551 (beta 2-blockade) decreased [La] and [Glc] 52 and 32% in resting -Fe rats, respectively. beta 2-Blockade attenuated the exercise-induced rise in [La] and decreased [Glc] 31% in exercising -Fe rats. [Ala] were unaffected by iron deficiency or exercise but decreased 24 and 18% because of beta 2-blockade in resting and exercising +Fe rats. Iron deficiency depleted resting liver glycogen concentration 45%, with no additional effect of exercise or beta 2-blockade. beta-Blockade decreased arterial insulin and increased arterial glucagon concentrations in resting -Fe and +Fe rats. During exercise glucagon concentration increased significantly more in -Fe than +Fe rats. Decreased arterial [La] with a corresponding decrease in arterial [Glc] in response to beta 2-blockade support the contention that lactate supply is critical to maintenance of euglycemia in -Fe rats at rest and during exercise.
Linderman
J K
JK
Department of Physical Education, University of California, Berkeley 94720.
Dallman
P R
PR
Rodriguez
R E
RE
Brooks
G A
GA
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000818:Animals; D001786:Blood Glucose / Q000378:metabolism*; D004837:Epinephrine / Q000097:blood; D005260:Female; D005934:Glucagon / Q000097:blood; D006003:Glycogen / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects*; D007328:Insulin / Q000097:blood; D007501:Iron / Q000494:pharmacology*; D000090463:Iron Deficiencies; D007545:Isoproterenol / Q000494:pharmacology; D007773:Lactates / Q000097:blood / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D008112:Liver Glycogen / Q000378:metabolism; D009132:Muscles / Q000187:drug effects / Q000378:metabolism*; D009638:Norepinephrine / Q000097:blood; D005082:Physical Exertion; D011412:Propanolamines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000319:Adrenergic beta-Antagonists; D001786:Blood Glucose; D007328:Insulin; D007773:Lactates; D008112:Liver Glycogen; D011412:Propanolamines; C026777:ICI 118551; D006003:Glycogen; D005934:Glucagon; D007501:Iron; D007545:Isoproterenol; D009638:Norepinephrine; D004837:Epinephrine