TRPV4 Forms a Novel Ca2+ Signaling Complex With
Ryanodine Receptors and BKCa Channels
by Scott Earley, Thomas J. Heppner, Mark T. Nelson, and Joseph E. Brayden
Circulation Research
Volume 97(12):1270-1279
December 9, 2005
Copyright © American Heart Association, Inc. All rights reserved.
Figure 1. Functional TRPV4 channels are present in rat cerebral artery smooth muscle. a,
Conventional whole-cell patch-clamp recording showing activation of an outwardly rectifying
current by 4α-PDD (5 μmol/L) in freshly isolated cerebral artery smooth muscle cells.
Scott Earley et al. Circ Res. 2005;97:1270-1279
Copyright © American Heart Association, Inc. All rights reserved.
Figure 2. 11,12 EET–induced increases in Ca2+ spark frequency and STOC frequency in cerebral
myocytes. a, Fractional change in [Ca2+] (F/Fo) for control and 11,12 EET–treated cells.
Scott Earley et al. Circ Res. 2005;97:1270-1279
Copyright © American Heart Association, Inc. All rights reserved.
Figure 3. EET-induced increases in Ca2+ spark and STOC frequency require extracellular Ca2+.
a, Effect of normal and reduced extracellular [Ca2+] on 11,12 EET–induced (300 nmol/L)
increases in Ca2+ spark frequency in the presence of the VDCC blocker diltiazem (30
μmol/L).*P<0.05 vs all other groups. n=8 to 16. b, Perforated patch–clamp recording showing the
effects of normal and reduced external [Ca2+] on 11,12 EET–induced increases in STOC
frequency in the presence of the VDCC blocker nisoldipine (1 μmol/L). c, Effect of normal and
reduced extracellular [Ca2+] on 11,12 EET–induced (300 nmol/L) increases in STOC frequency
during VDCC inhibition.*P<0.05 vs all other groups, #P<0.05 vs 11,12 EET–treated cells in normal
external [Ca2+] solution. n=5 for all groups.
Scott Earley et al. Circ Res. 2005;97:1270-1279
Copyright © American Heart Association, Inc. All rights reserved.
Figure 4. The TRPV antagonist RR blocks 11,12 EET– and 4α-PDD–induced increases in STOC
frequency. a, Example patch-clamp recording demonstrating that RR (1 μmol/L) blocks 11,12
EET–induced increases in STOC frequency. b, Summary data (n=4 for each group).
Scott Earley et al. Circ Res. 2005;97:1270-1279
Copyright © American Heart Association, Inc. All rights reserved.
Figure 5. TRPV4 downregulation attenuates 11,12 EET–activated whole-cell currents. a, Wholecell currents activated by 11,12 EET (300 nmol/L) in smooth muscle cells isolated from TRPV4
sense-treated cerebral arteries.
Scott Earley et al. Circ Res. 2005;97:1270-1279
Copyright © American Heart Association, Inc. All rights reserved.
Figure 6. TRPV4 downregulation blocks 11,12 EET–induced increases in Ca2+ spark and STOC
frequency. a, Fractional change in [Ca2+] (F/Fo) before and after administration of 11,12 EET (300
nmol/L) for TRPV4 sense- and antisense-treated vessels. b, Effect of 11,12 EET (300 nmol/L) on
Ca2+ spark frequency in TRPV4 sense and antisense-treated arteries.
Scott Earley et al. Circ Res. 2005;97:1270-1279
Copyright © American Heart Association, Inc. All rights reserved.
Figure 7. TRPV4 downregulation blocks 11,12 EET–induced smooth muscle hyperpolarization
and vasodilation. a, Recordings of smooth muscle cell membrane potential (Em) following 11,12
EET administration for TRPV4 sense- and antisense-treated arteries pressurized to 60 mm Hg. b,
Effect of 11,12 EET on Em in sense- and antisense-treated vessels. *P<0.05 vs sense control,
#P<0.05 vs sense 11,12 EET treated. n=6 (sense) or n=4 (antisense). c, 11,12 EET–induced
vasodilatory responses of TRPV4 sense- and antisense-treated cerebral arteries.
Scott Earley et al. Circ Res. 2005;97:1270-1279
Copyright © American Heart Association, Inc. All rights reserved.
Figure 8. Proposed mechanism for TRPV4-dependent, EET-induced smooth muscle
hyperpolarization.
Scott Earley et al. Circ Res. 2005;97:1270-1279
Copyright © American Heart Association, Inc. All rights reserved.