Effects of length change on intracellular Ca2+ transients in ferret ventricular muscle treated with 2,3-butanedione monoxime (BDM).
Quick release of the right ventricular papillary muscle of ferrets, injected with aequorin, from Lmax (initial length) to 92% Lmax during twitch response produced an extra-light signal of aequorin. 2,3-Butanedione monoxime (BDM) at 10 mM decreased the peak tension to less than 10% of that in control and the light signal to 70%. In the BDM-treated muscle, the extra-light in response to the quick release did not occur. A quick stretch from Lmax to 103% Lmax, in the presence and absence of BDM, did not cause any changes in the light signal. The results indicate that the extra-light signal in the quick release is tension dependent. The tension reduction by the quick release decreases the affinity of troponin-C (Tn-C) for Ca2+ without affecting Ca2+ handling system in intact cardiac muscle.
Kurihara
S
S
Department of Physiology, Jikei University School of Medicine, Tokyo, Japan.
Saeki
Y
Y
Hongo
K
K
Tanaka
E
E
Sudo
N
N
D000331:Aequorin / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002801:Cholinesterase Reactivators / Q000494:pharmacology*; D003931:Diacetyl / Q000031:analogs & derivatives* / Q000494:pharmacology; D005289:Ferrets / Q000033:anatomy & histology / Q000502:physiology*; D006352:Heart Ventricles / Q000187:drug effects; D009200:Myocardial Contraction / Q000187:drug effects*; D010210:Papillary Muscles / Q000187:drug effects*; D014336:Troponin / Q000378:metabolism; D019209:Troponin C
D002801:Cholinesterase Reactivators; D014336:Troponin; D019209:Troponin C; C004717:diacetylmonoxime; D000331:Aequorin; D003931:Diacetyl; D002118:Calcium