Spontaneous "second wind" and glucose-induced second "second wind" in McArdle disease: oxidative mechanisms.

Abstract

BACKGROUND:

Blocked glycogen breakdown in McArdle disease impairs oxidative as well as anaerobic metabolism, but the contribution of impaired oxidative phosphorylation to everyday symptoms of McArdle disease remains poorly defined.

OBJECTIVE:

To evaluate the oxidative implications of the spontaneous second wind and variables that influence the development of this typical feature of McArdle disease.

DESIGN:

Assessment of exercise and oxidative capacity (.VO(2)) before and after the spontaneous "second wind" and with a glucose infusion after a spontaneous second wind.

PATIENTS:

Eight patients with complete myophosphorylase deficiency and 1 unique patient with 3% of normal myophosphorylase activity.

MAIN OUTCOME MEASURES:

Work capacity,.VO(2), heart rate, cardiac output.

RESULTS:

All patients with complete myophosphorylase deficiency (1) had low peak.VO(2) (mean +/- SD, 13.0 +/- 2.0 mL. kg(-1). min(-1)) in the first 6 to 8 minutes of exercise; (2) achieved a spontaneous second wind with increased exercise capacity between 8 and 12 minutes of exercise due to a more than 25% increase in peak.VO(2) (16.5 +/- 3.1 mL. kg(-1). min(-1)); and (3) with glucose infusion after a spontaneous second wind, experienced a further more than 20% increase in oxidative capacity (.VO(2), 19.9 +/- 3.9 mL. kg(-1). min(-1)). In the patient with residual myophosphorylase,.VO(2) (22.2 mL. kg(-1). min(-1)) in the first 6 to 8 minutes of exercise was approximately 2-fold higher than the mean of patients lacking myophosphorylase, and no significant improvement in exercise and oxidative capacity accompanied prolonged exercise or glucose infusion.

CONCLUSIONS:

First, the spontaneous second wind and the glucose-induced second second wind in McArdle disease are due to substrate-dependent increases in muscle oxidative capacity. Second, by providing glycogen-derived pyruvate, a small amount of residual myophosphorylase activity normalizes the oxidative deficit of complete myophosphorylase deficiency and virtually eliminates the spontaneous second wind and glucose-induced second second wind.

• Authors: Ronald G Haller, John Vissing
• Journal: Archives of neurology (Arch Neurol) Vol. 59 Issue 9 Pg. 1395-402 (Sep 2002) ISSN: 0003-9942 [Print] United States
• PMID: 12223025 (Publication Type: Clinical Trial, Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Lactic Acid
• Glycogen Phosphorylase, Muscle Form
• Glucose
• Oxygen

Topics

• Adult
• Anaerobic Threshold (physiology)
• Cardiac Output (physiology)
• Exercise (physiology)
• Female
• Glucose (pharmacology)
• Glycogen Phosphorylase, Muscle Form (deficiency)
• Glycogen Storage Disease Type V (metabolism)
• Heart Rate (physiology)
• Humans
• Lactic Acid (blood)
• Male
• Oxidation-Reduction
• Oxygen (blood)
• Oxygen Consumption (physiology)
• Work Capacity Evaluation