PURPOSE: To investigate endothelin 1 (Et1)-dependent Ca(2+)-signaling at the cellular and subcellular levels in retinal arteriolar myocytes. METHODS: Et1 responses were imaged from Fluo-4-loaded smooth muscle in isolated segments of rat retinal arteriole using confocal laser microscopy. RESULTS: Basal [Ca(2+)](i), subcellular Ca(2+)-sparks, and cellular Ca(2+)-oscillations were all increased during exposure to Et1 (10 nM). Ca(2+)-spark frequency was also increased by 90% by 10 nM Et1. The increase in oscillation frequency was concentration dependent and was inhibited by the EtA receptor (Et(A)R) blocker BQ123 but not by the EtB receptor antagonist BQ788. Stimulation of Ca(2+)-oscillations by Et1 was inhibited by a phospholipase C blocker (U73122; 10 μM), two inhibitors of inositol 1,4,5-trisphosphate receptors (IP(3)Rs), xestospongin C (10 μM), 2-aminoethoxydiphenyl borate (100 μM), and tetracaine (100 μM), a blocker of ryanodine receptors (RyRs). CONCLUSIONS: Et1 stimulates Ca(2+)-sparks and oscillations through Et(A)Rs. The underlying mechanism involves the activation of phospholipase C and both IP(3)Rs and RyRs, suggesting crosstalk between these Ca(2+)-release channels. These findings suggest that phasic Ca(2+)-oscillations play an important role in the smooth muscle response to Et1 within the retinal microvasculature and support an excitatory, proconstrictor role for Ca(2+)-sparks in these vessels.
PURPOSE: To investigate endothelin 1 (Et1)-dependent Ca(2+)-signaling at the cellular and subcellular levels in retinal arteriolar myocytes. METHODS:Et1 responses were imaged from Fluo-4-loaded smooth muscle in isolated segments of rat retinal arteriole using confocal laser microscopy. RESULTS: Basal [Ca(2+)](i), subcellular Ca(2+)-sparks, and cellular Ca(2+)-oscillations were all increased during exposure to Et1 (10 nM). Ca(2+)-spark frequency was also increased by 90% by 10 nM Et1. The increase in oscillation frequency was concentration dependent and was inhibited by the EtA receptor (Et(A)R) blocker BQ123 but not by the EtB receptor antagonist BQ788. Stimulation of Ca(2+)-oscillations by Et1 was inhibited by a phospholipase C blocker (U73122; 10 μM), two inhibitors of inositol 1,4,5-trisphosphate receptors (IP(3)Rs), xestospongin C (10 μM), 2-aminoethoxydiphenyl borate (100 μM), and tetracaine (100 μM), a blocker of ryanodine receptors (RyRs). CONCLUSIONS:Et1 stimulates Ca(2+)-sparks and oscillations through Et(A)Rs. The underlying mechanism involves the activation of phospholipase C and both IP(3)Rs and RyRs, suggesting crosstalk between these Ca(2+)-release channels. These findings suggest that phasic Ca(2+)-oscillations play an important role in the smooth muscle response to Et1 within the retinal microvasculature and support an excitatory, proconstrictor role for Ca(2+)-sparks in these vessels.
Authors: M Keith Wilkerson; Thomas J Heppner; Adrian D Bonev; Mark T Nelson Journal: Am J Physiol Heart Circ Physiol Date: 2005-08-19 Impact factor: 4.733
Authors: Rebecca E Haddock; T Hilton Grayson; Therese D Brackenbury; Kate R Meaney; Craig B Neylon; Shaun L Sandow; Caryl E Hill Journal: Am J Physiol Heart Circ Physiol Date: 2006-06-30 Impact factor: 4.733
Authors: Onesmo B Balemba; Thomas J Heppner; Adrian D Bonev; Mark T Nelson; Gary M Mawe Journal: Am J Physiol Gastrointest Liver Physiol Date: 2006-05-18 Impact factor: 4.052
Authors: Mary K McGahon; Durga P Dash; Aruna Arora; Noreen Wall; Jennine Dawicki; David A Simpson; C Norman Scholfield; J Graham McGeown; Tim M Curtis Journal: Circ Res Date: 2007-02-09 Impact factor: 17.367
Authors: Michael Francis; Xun Qian; Chimène Charbel; Jonathan Ledoux; J C Parker; Mark S Taylor Journal: Am J Physiol Cell Physiol Date: 2012-04-25 Impact factor: 4.249
Authors: Luke B Potts; Yi Ren; Guangrong Lu; Enoch Kuo; Ellen Ngo; Lih Kuo; Travis W Hein Journal: Invest Ophthalmol Vis Sci Date: 2012-05-17 Impact factor: 4.799
Authors: Michael Stewart; Maurice Needham; Peter Bankhead; Tom A Gardiner; C Norman Scholfield; Tim M Curtis; J Graham McGeown Journal: Invest Ophthalmol Vis Sci Date: 2012-05-17 Impact factor: 4.799
Authors: John N Barrett; Samantha Rincon; Jayanti Singh; Cristina Matthewman; Julio Pasos; Ellen F Barrett; Suhrud M Rajguru Journal: J Neurophysiol Date: 2018-04-18 Impact factor: 2.714
Authors: Tim M Curtis; Declan McLaughlin; Michael O'Hare; Joanna Kur; Peter Barabas; Gordon Revolta; C Norman Scholfield; J Graham McGeown; Mary K McGahon Journal: J Vis Exp Date: 2018-07-14 Impact factor: 1.355