PMID- 8403253
OWN - NLM
STAT- MEDLINE
DCOM- 19931118
LR  - 20191210
IS  - 0009-7330 (Print)
IS  - 0009-7330 (Linking)
VI  - 73
IP  - 5
DP  - 1993 Nov
TI  - Sarcoplasmic reticulum Ca2+ uptake and thapsigargin sensitivity in permeabilized 
      rabbit and rat ventricular myocytes.
PG  - 820-8
AB  - Ca2+ uptake by the sarcoplasmic reticulum (SR) and free [Ca2+] were measured 
      simultaneously with indo 1 and a Ca(2+)-selective minielectrode in suspensions of 
      permeabilized rabbit or rat ventricular myocytes (approximately 10 mg/mL 
      protein). In the presence of 25 mumol/L ruthenium red and 10 mmol/L oxalate, the 
      Km for Ca2+ uptake by the SR was approximately 250 nmol/L in rabbit and rat 
      ventricular myocytes. The maximal Ca2+ uptake rate was 2.4 times higher in rat 
      than in rabbit. Addition of 5 nmol thapsigargin (TG) per milligram cell protein 
      abolished Ca2+ uptake completely in both species. The [TG] necessary for a 
      half-maximal reduction of the uptake rate (K1/2) was 55 pmol/mg cell protein for 
      rabbit and 390 pmol/mg cell protein for rat. Assuming that the number of pump 
      sites is two times the concentration of TG necessary to inhibit half of the Ca2+ 
      pump activity (ie, the TG affinity is very high), the density of pump sites is 
      7.7 mumol/kg wet wt for rabbit and 54.6 mumol/kg wet wt for rat. Despite a 
      fivefold decrease of the Ca2+ uptake rate by a submaximal [TG], the permeabilized 
      myocytes were still able to lower the free [Ca2+] to < 150 nmol/L from a peak 
      value > 10 mumol/L. The relative inhibition of Ca2+ uptake by TG did not depend 
      on the free [Ca2+]. Addition of more than 5 nmol TG per milligram cell protein 
      abolished Ca2+ uptake by the SR completely in < 15 seconds and reduced the uptake 
      rate by 95% in 5 seconds.(ABSTRACT TRUNCATED AT 250 WORDS)
FAU - Hove-Madsen, L
AU  - Hove-Madsen L
AD  - Division of Biomedical Sciences, University of California, Riverside.
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  - Circ Res
JT  - Circulation research
JID - 0047103
RN  - 0 (Indoles)
RN  - 0 (Terpenes)
RN  - 67526-95-8 (Thapsigargin)
RN  - EC 7.2.2.10 (Calcium-Transporting ATPases)
RN  - SY7Q814VUP (Calcium)
RN  - X9TLY4580Z (cyclopiazonic acid)
SB  - IM
MH  - Animals
MH  - Calcium/*metabolism
MH  - Calcium-Transporting ATPases/*antagonists & inhibitors
MH  - In Vitro Techniques
MH  - Indoles/pharmacology
MH  - Myocardium/*metabolism
MH  - Permeability
MH  - Rabbits
MH  - Rats
MH  - Rats, Sprague-Dawley
MH  - Sarcoplasmic Reticulum/drug effects/*metabolism
MH  - Terpenes/*pharmacology
MH  - Thapsigargin
EDAT- 1993/11/01 00:00
MHDA- 1993/11/01 00:01
CRDT- 1993/11/01 00:00
PHST- 1993/11/01 00:00 [pubmed]
PHST- 1993/11/01 00:01 [medline]
PHST- 1993/11/01 00:00 [entrez]
AID - 10.1161/01.res.73.5.820 [doi]
PST - ppublish
SO  - Circ Res. 1993 Nov;73(5):820-8. doi: 10.1161/01.res.73.5.820.