Pharmacological Profiling of Store‐Operated Ca²⁺ Entry in Retinal Arteriolar Smooth Muscle

Abstract

The pharmacological profile of SOCE in retinal arteriolar smooth muscle appears unique when compared with other vascular tissues. This suggests that the molecular mechanisms underlying SOCE can differ, even in closely related tissues. Taken together, the pharmacological and molecular data are most consistent with involvement of TRPC1 in SOCE, although involvement of ORAI or other TRPC channels cannot be excluded.

TRPV2 Channels Contribute to Stretch-Activated Cation Currents and Myogenic Constriction in Retinal Arterioles

“…Retinal arterioles were isolated as previously described. 23,24 Experiments were carried out within 8 hours of vessel isolation.…”

“…To assess mechanoTRP channel mRNA expression, isolated retinal arterioles were collected under microscopic magnification and transferred into total RNA extraction buffer (RNeasy Mini Kit; Qiagen, Crawley, UK). Reverse transcription-polymerase chain reaction was carried out according to previously established protocols within our laboratory 24,25 using primers for specific mechanoTRP channels of interest (Supplementary Table S1).…”

“…Ca 2þ imaging experiments were performed as previously described. [23][24][25] Briefly, isolated retinal arterioles were loaded with 5 lM fura-2AM (Abcam) for 2 hours at room temperature. This exclusively loads the VSMC layer of these vessels.…”

“…We have previously demonstrated mRNA expression of TRPC1, TRPV1, and TRPV2 in these vessels, whilst transcripts for TRPC5, TRPC6, and TRPA1 could not be detected. 24 This work was extended to investigate the mRNA expression of other putative mechanoTRP channels, including TRPV4, TRPM4, TRPM7, and TRPP1 (PKD2). All of these channels were found to be expressed at the mRNA level in retinal arterioles with the exception of TRPM4 ( Fig.…”

Prostaglandin induced changes in the tone of porcine retinal arterioles in vitro involve other factors than calcium activity in perivascular cells

“…Similarly, apart from an increase in the amplitude of fluorescence waves in the presence of ibuprofen, PGF 2 a induced calcium activity in the PVCs in the presence of the IP 3 R blocker 2-APB was similar whether the experiments had been conducted in the presence of ibuprofen or not. The fact that the L-type calcium channel blocker nifedipine and the non-specific cation channel blocker LOE908 induced relaxation of the retinal arterioles suggests that these calcium channels located in the plasma membrane are involved in the maintenance of basal tone (Potts et al, 2012) as opposed to calcium channels related to the endoplasmic reticulum (McGahon et al, 2012). However, the addition of Ca 2þ antagonists was unable to increase relaxation beyond the relaxing effect that could be obtained by PGE 2 alone which suggests that the relaxing effects of Ca 2þ antagonists and PGE 2 might be linked and had been saturated during the experiments.…”