Effects of metallothionein on action potentials of anoxic and reoxygenated papillary muscles of guinea pigs.
OBJECTIVE
To study anti-arrhythmic effects of metallothionein (MT).


METHODS
Standard microelectrode technique was used to study the effects of MT on action potentials (AP) in anoxic and reoxygenated papillary muscles of guinea pigs.


RESULTS
MT (0.02 mmol.L-1) had no effects on AP of the normal papillary muscles; when the muscles were exposed to ischemic solution without MT, there was a marked shortening of action potential duration (APD) at 20%, 50%, and 90% of repolarization (APD20, APD50, APD90) from 82 +/- 7 to 37 +/- 7, 131 +/- 35 to 63 +/- 11, and 167 +/- 12 to 100 +/- 19 ms, respectively, (P < 0.01); and an obvious reduction of resting potential (RP), action potential amplitude (APA), and the maximal upstroke velocity of phase 0 (Vmax) from -92 +/- 9 to -63 +/- 12 mV, 135 +/- 13 to 80 +/- 8 mV, and 286 +/- 55 to 164 +/- 42 V.s-1, respectively (P < 0.01). However, in the presence of MT, the AP parameters (RP, APA, and Vmax) changed from -63 +/- 2 to -82 +/- 1 mV, 80 +/- 8 to 104 +/- 25 mV, and 164 +/- 42 to 237 +/- 43 V.s-1, respectively, (P < 0.01), except that APD20, APD50, and APD90 shortened further from 37 +/- 7 to 12 +/- 3, 63 +/- 11 to 28 +/- 7, and 100 +/- 19 to 82 +/- 11 mV, respectively (P < 0.01). MT decreased the incidence of automaticity during reoxygenation from 91% to 33%.


CONCLUSIONS
MT possesses a calcium regulatory property.
Li
S M
SM
Heart Center, Beijing Red Cross Chaoyang Hospital, Capital Medical University, China.
Liu
B
B
Liu
X L
XL
Hu
D Y
DY
Tang
C S
CS
D000200:Action Potentials / Q000187:drug effects; D000818:Animals; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism; D015687:Cell Hypoxia; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008668:Metallothionein / Q000494:pharmacology*; D010210:Papillary Muscles / Q000502:physiology*
D000889:Anti-Arrhythmia Agents; D008668:Metallothionein; D002118:Calcium