Sarcoplasmic reticulum Ca2+ uptake and thapsigargin sensitivity in permeabilized rabbit and rat ventricular myocytes.
Population
Suspensions of permeabilized rabbit or rat ventricular myocytes (approximately 10 mg/mL protein)
Design
Preclinical
Authors
Discussion
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Member takes
Implication
Species differences in SR Ca2+ uptake rates caution against rodent-to-rabbit extrapolation; leaves open thapsigargin dosing for human translation.
Key Points
- To measure Ca2+ uptake by the sarcoplasmic reticulum in permeabilized rabbit and rat ventricular myocytes and evaluate thapsigargin sensitivity.
- Simultaneous measurement of Ca2+ uptake and free [Ca2+] in permeabilized myocytes from rabbit and rat.
- Evaluation of Ca2+ uptake rate and thapsigargin effects using indo 1 and a Ca(2+)-selective minielectrode.
- Determination of Km for Ca2+ uptake and calculation of pump site density based on thapsigargin inhibition.
- Km for Ca2+ uptake was 250 nmol/L in both species.
- Maximal Ca2+ uptake rate was 2.4 times higher in rat than in rabbit myocytes.
- 5 nmol of thapsigargin per milligram cell protein abolished Ca2+ uptake completely in both species.
Structured PICO
P
Population
Suspensions of permeabilized rabbit or rat ventricular myocytes (approximately 10 mg/mL protein)
I
Intervention
Thapsigargin (TG)
O
Outcome
Ca2+ uptake by the sarcoplasmic reticulum (SR) and free [Ca2+]surrogate
Thapsigargin potently inhibits sarcoplasmic reticulum Ca2+ uptake in both rabbit and rat ventricular myocytes, revealing species-specific differences in pump density and maximal uptake rates.
Cite This Study
Hove‐Madsen et al. (1993) studied this question.