Abstract
We determined the effect of the dihydropyridine L-type Ca channel agonist BAY K 8644 (BAY) on excitation-contraction (E-C) coupling in isolated ferret ventricular myocytes using whole cell voltage clamp. The sarcoplasmic reticulum (SR) Ca load during the test pulses, assessed by caffeine-induced contractures, was similar in the presence and absence of BAY, with extracellular Ca concentration lowered from 3 to 1 mM in BAY. The relationship between L-type Ca current (I(Ca)) and contraction was assessed, with current and contractions measured during depolarizations from -40 to between -30 and +50 mV after a conditioning train (to ensure constant SR Ca load). BAY shifted the current-contraction relationship downward, such that, for a given I(Ca) and SR Ca load, the contraction elicited was much smaller in the presence of BAY. BAY also induced a characteristic negative shift in the current-voltage relationship. We conclude that BAY decreases the efficacy of a given Ca current to induce SR Ca release during E-C coupling in ferret cardiac tissue (in contrast to the BAY-induced increase of resting SR Ca release). This may reflect an alteration in the state of the SR Ca release channel due to BAY binding to dihydropyridine receptors.
| Original language | English (US) |
|---|---|
| Journal | American Journal of Physiology - Cell Physiology |
| Volume | 270 |
| Issue number | 3 39-3 |
| State | Published - Mar 1996 |
| Externally published | Yes |
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Keywords
- calcium current
- dihydropyridine
- ferret ventricular myocytes
- sarcoplasmic reticulum
ASJC Scopus subject areas
- Clinical Biochemistry
- Cell Biology
- Physiology
- Physiology (medical)
Cite this
BAY K 8644 depresses excitation-contraction coupling in cardiac muscle. / Mccall, E.; Bers, Donald M.
In: American Journal of Physiology - Cell Physiology, Vol. 270, No. 3 39-3, 03.1996.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - BAY K 8644 depresses excitation-contraction coupling in cardiac muscle
AU - Mccall, E.
AU - Bers, Donald M
PY - 1996/3
Y1 - 1996/3
N2 - We determined the effect of the dihydropyridine L-type Ca channel agonist BAY K 8644 (BAY) on excitation-contraction (E-C) coupling in isolated ferret ventricular myocytes using whole cell voltage clamp. The sarcoplasmic reticulum (SR) Ca load during the test pulses, assessed by caffeine-induced contractures, was similar in the presence and absence of BAY, with extracellular Ca concentration lowered from 3 to 1 mM in BAY. The relationship between L-type Ca current (I(Ca)) and contraction was assessed, with current and contractions measured during depolarizations from -40 to between -30 and +50 mV after a conditioning train (to ensure constant SR Ca load). BAY shifted the current-contraction relationship downward, such that, for a given I(Ca) and SR Ca load, the contraction elicited was much smaller in the presence of BAY. BAY also induced a characteristic negative shift in the current-voltage relationship. We conclude that BAY decreases the efficacy of a given Ca current to induce SR Ca release during E-C coupling in ferret cardiac tissue (in contrast to the BAY-induced increase of resting SR Ca release). This may reflect an alteration in the state of the SR Ca release channel due to BAY binding to dihydropyridine receptors.
AB - We determined the effect of the dihydropyridine L-type Ca channel agonist BAY K 8644 (BAY) on excitation-contraction (E-C) coupling in isolated ferret ventricular myocytes using whole cell voltage clamp. The sarcoplasmic reticulum (SR) Ca load during the test pulses, assessed by caffeine-induced contractures, was similar in the presence and absence of BAY, with extracellular Ca concentration lowered from 3 to 1 mM in BAY. The relationship between L-type Ca current (I(Ca)) and contraction was assessed, with current and contractions measured during depolarizations from -40 to between -30 and +50 mV after a conditioning train (to ensure constant SR Ca load). BAY shifted the current-contraction relationship downward, such that, for a given I(Ca) and SR Ca load, the contraction elicited was much smaller in the presence of BAY. BAY also induced a characteristic negative shift in the current-voltage relationship. We conclude that BAY decreases the efficacy of a given Ca current to induce SR Ca release during E-C coupling in ferret cardiac tissue (in contrast to the BAY-induced increase of resting SR Ca release). This may reflect an alteration in the state of the SR Ca release channel due to BAY binding to dihydropyridine receptors.
KW - calcium current
KW - dihydropyridine
KW - ferret ventricular myocytes
KW - sarcoplasmic reticulum
UR - http://www.scopus.com/inward/record.url?scp=0029874395&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0029874395&partnerID=8YFLogxK
M3 - Article
C2 - 8638669
AN - SCOPUS:0029874395
VL - 270
JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology
SN - 1931-857X
IS - 3 39-3
ER -