PMID- 8368279
OWN - NLM
STAT- MEDLINE
DCOM- 19931001
LR  - 20191210
IS  - 0002-9513 (Print)
IS  - 0002-9513 (Linking)
VI  - 265
IP  - 2 Pt 1
DP  - 1993 Aug
TI  - Twitch-dependent SR Ca accumulation and release in rabbit ventricular myocytes.
PG  - C533-40
AB  - Using caffeine-induced contractures (Ccaf) and thapsigargin (TG), we estimated 
      the fraction of sarcoplasmic reticulum (SR) Ca released at one twitch and also 
      the number of twitches required to reload a Ca-depleted SR. Similar results were 
      obtained for twitches or intracellular Ca (Cai) transient with the fluorescent 
      indicator, indo 1. Sustained exposure to 10 mM caffeine completely depletes the 
      SR of Ca in < 5 s (as assessed by a second Ccaf). After such Ca depletion, four 
      to five twitches are necessary to reload the SR to the steady-state level (with a 
      twitch constant, tau = 1.6 twitches). We also determined the time required for 
      complete inhibition of the SR Ca-adenosinetriphosphatase (ATPase) by TG. After SR 
      Ca depletion, 5 microM TG was applied for different periods of time before a 
      train of "reloading" twitches. A TG exposure period of 90 s was sufficient to 
      completely prevent Ccaf after these reloading twitches. When SR is Ca depleted, 
      the twitch is larger in the presence of TG, indicating that the SR Ca-ATPase can 
      limit the ability of Ca influx to activate contraction. To assess SR Ca released 
      at one twitch in cells with normally Ca-loaded SR, 5 microM TG was applied for 90 
      s to prevent SR Ca reuptake. Then one or several twitches were activated (causing 
      SR Ca release, but with reuptake completely blocked). After the twitch (or 
      train), a Ccaf was used to assess remaining SR Ca.(ABSTRACT TRUNCATED AT 250 
      WORDS)
FAU - Bassani, J W
AU  - Bassani JW
AD  - Department of Physiology, Loyola University School of Medicine, Maywood, Illinois 
      63304.
FAU - Bassani, R A
AU  - Bassani RA
FAU - Bers, D M
AU  - Bers DM
LA  - eng
GR  - HL-30077/HL/NHLBI NIH HHS/United States
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PT  - Research Support, U.S. Gov't, P.H.S.
PL  - United States
TA  - Am J Physiol
JT  - The American journal of physiology
JID - 0370511
RN  - 0 (Terpenes)
RN  - 67526-95-8 (Thapsigargin)
RN  - EC 7.2.2.10 (Calcium-Transporting ATPases)
RN  - SY7Q814VUP (Calcium)
SB  - IM
MH  - Animals
MH  - Calcium/*metabolism
MH  - Calcium-Transporting ATPases/antagonists & inhibitors
MH  - Electric Stimulation
MH  - Heart Ventricles
MH  - Homeostasis
MH  - Male
MH  - *Myocardial Contraction
MH  - Myocardium/cytology/*metabolism
MH  - Rabbits
MH  - Sarcoplasmic Reticulum/*metabolism
MH  - Terpenes/pharmacology
MH  - Thapsigargin
MH  - Time Factors
EDAT- 1993/08/01 00:00
MHDA- 1993/08/01 00:01
CRDT- 1993/08/01 00:00
PHST- 1993/08/01 00:00 [pubmed]
PHST- 1993/08/01 00:01 [medline]
PHST- 1993/08/01 00:00 [entrez]
AID - 10.1152/ajpcell.1993.265.2.C533 [doi]
PST - ppublish
SO  - Am J Physiol. 1993 Aug;265(2 Pt 1):C533-40. doi: 10.1152/ajpcell.1993.265.2.C533.