P2X receptor-stimulated calcium responses in preglomerular vascular smooth muscle cells involves 20-hydroxyeicosatetraenoic acid.
The current study tested the hypothesis that endogenous 20-hydroxyeicosatetraenoic acid (20-HETE) contributes to the increase in intracellular calcium ([Ca2+]i) elicited by P2X receptor activation in renal microvascular smooth muscle cells. Vascular smooth muscle cells obtained from rats were loaded with fura-2 and studied using standard single cell fluorescence microscopy. Basal renal myocyte [Ca2+]i averaged 96 +/- 5 nM. ATP (10 and 100 microM) increased vascular smooth muscle cell [Ca2+]i by 340 +/- 88 and 555 +/- 80 nM, respectively. The cytochrome P450 hydroxylase inhibitor, N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS), or the 20-HETE antagonist, 20-hydroxyeicosa-6(Z),15(Z)-dienoic acid (20-HEDE), significantly attenuated the peak myocyte [Ca2+]i responses to 10 and 100 microM ATP. ATP (100 microM) increased vascular smooth muscle cell [Ca2+]i by 372 +/- 93 and 163 +/- 55 nM in the presence of DDMS or 20-HEDE, respectively. The P2X receptor agonist, alpha,beta-methylene-ATP (10 microM), increased myocyte [Ca2+]i by 78 +/- 12 nM, and this response was significantly attenuated by DDMS (40 +/- 15 nM). In contrast, the vascular smooth muscle cell [Ca2+]i evoked by the P2Y agonist, UTP (100 microM), was not altered by DDMS or 20-HEDE. The effect of 20-HETE on [Ca2+]i was also assessed, and the peak increases in [Ca2+]i averaged 62 +/- 12 and 146 +/- 70 nM at 20-HETE concentrations of 1 and 10 microM, respectively. These results demonstrate that 20-HETE plays a significant role in the renal microvascular smooth muscle cell [Ca2+]i response to P2X receptor activation.
Zhao
Xueying
X
Vascular Biology Center, Medical College of Georgia, Augusta, GA 30912-2500, USA.
Falck
John R
JR
Gopal
V Raj
VR
Inscho
Edward W
EW
Imig
John D
JD
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000577:Amides / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002196:Capillaries / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D002469:Cell Separation; D006893:Hydroxyeicosatetraenoic Acids / Q000037:antagonists & inhibitors / Q000502:physiology*; D066298:In Vitro Techniques; D007678:Kidney Glomerulus / Q000098:blood supply / Q000166:cytology / Q000378:metabolism*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D058910:Purinergic P2 Receptor Agonists; D051381:Rats; D017207:Rats, Sprague-Dawley; D058469:Receptors, Purinergic P2X; D012079:Renal Circulation; D013050:Spectrometry, Fluorescence; D013450:Sulfones / Q000494:pharmacology
D000577:Amides; D006893:Hydroxyeicosatetraenoic Acids; D058910:Purinergic P2 Receptor Agonists; D058469:Receptors, Purinergic P2X; D013450:Sulfones; C055987:20-hydroxy-5,8,11,14-eicosatetraenoic acid; D000255:Adenosine Triphosphate; C117975:DDMS; C002630:alpha,beta-methyleneadenosine 5'-triphosphate; D002118:Calcium