Rapid changes in plasma potassium during a game of squash.
1. The game of squash has recently been associated with a high incidence of ventricular arrhythmias and sudden death. To investigate this further, plasma catecholamines and potassium (K+) were monitored during a game of squash in six normal volunteers. 2. No cardiac arrhythmias were seen in this study despite the subjects reaching maximum heart rates of 181 +/- 5 beats/min (mean +/- SEM). 3. During exercise, plasma K+ rose from 3.82 +/- 0.16 to 4.29 +/- 0.2 mmol/l, but after 90 s rest this fell to 3.68 +/- 0.28 mmol/l and after 180 s to 3.44 +/- 0.17 mmol/l. This rapid K+ shift could not be accounted for by generalized changes in venous acid-base status or by changes in venous plasma catecholamines. Although pretreatment with a beta 2-antagonist caused the overall plasma K+ levels to be higher, it had no significant effect on the fall in plasma K+ after exercise. 4. Such rapid K+ shifts after exercise might contribute to arrhythmogenesis in susceptible individuals. The precise mechanism of the fall in K+ after exercise remains undetermined, but it seems not to involve catecholamines stimulating beta 2-adrenoceptors and is more likely to be due to increased skeletal muscle blood flow and/or intracellular acidosis.
D000319:Adrenergic beta-Antagonists / Q000494:pharmacology; D000328:Adult; D001145:Arrhythmias, Cardiac / Q000209:etiology; D004837:Epinephrine / Q000097:blood; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D009638:Norepinephrine / Q000097:blood; D010100:Oxygen / Q000097:blood; D011188:Potassium / Q000097:blood*; D011412:Propanolamines / Q000494:pharmacology; D013177:Sports; D013997:Time Factors
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; C026777:ICI 118551; D011188:Potassium; D010100:Oxygen; D009638:Norepinephrine; D004837:Epinephrine