The pressure-induced vasoconstriction or “myogenic response” of small arteries and arterioles is thought to be a primary mechanism contributing to blood flow autoregulation in many vascular beds. In cerebral arteries, activation of TRPC6 (1) and TRPM4 (2) channels has been shown to contribute to pressure-induced smooth muscle cell depolarisation and myogenic vasoconstriction. To date, no studies have addressed the role of TRP channels in mediating arteriolar myogenic responses. In the present study, we have begun to define the molecular and functional expression of mechanosensitive TRP channels in retinal arteriolar smooth muscle cells. Using mechanical dissociation, arteriolar enriched samples of rat retinae were screened (using RT-PCR) for expression of mRNA encoding a number of known mechanosensitive TRP channels. mRNA transcripts for TRPC1, TRPM7, TRPV1, TRPV2, TRPV4 and TRPP1 channels were detected. In contrast to larger resistance arteries, retinal arterioles do not appear to express TRPC6 or TRPM4 channels. Immunohistochemical staining of whole flat mounts of rat retinae revealed cytosolic and membrane expression of TRPV1, TRPV2, TRPP1 and TRPM7 in arteriolar smooth muscle cells surrounding arterioles, while TRPV1, TRPV2, TRPV4 and TRPM7 were also detected in the endothelial cells lining arterioles, capillaries and venules. These expression patterns were confirmed using multiple antibodies to different epitopes within the respective channels. Whole-cell patch-clamp recordings were subsequently made from rat retinal arteriolar smooth muscle cells embedded within isolated arteriolar segments, using Cs+ based internal and external solutions containing 10 µM nimodipine, and 2 s voltage ramps from -80 to +80 mV. Application of the TRPV2 agonist, delta-9-tetrahydrocannabinol (Δ9THC; 10 µM), elicited an increase in inward current at negative voltages, from -43.9 ± 16.7 pA/pF at -80 mV in absence of Δ9THC to 61.9 ± 22.9 pA/pF in the presence of Δ9THC (mean ± SEM, n=9, P=0.03, paired Student’s t-test) and in the outward current at positive voltages (88.6 ± 40.6 pA/pF in the absence of Δ9THC compared to 125.8 ± 55.5 pA/pF at +80 mV in the presence of Δ9THC; P=0.04). The current activated by Δ9THC was outwardly rectifying and reversed at -9.7 ± 4.0 mV. Both the inward and outward portions of the current elicited by Δ9THC were inhibited by pre-incubation of the vessel with the TRPV2 inhibitor, tranilast (10 µM; n=5). Our results suggest that retinal arteriolar smooth muscle cells express a range of mechanosensitive TRP channels and that TRPV2 channels may be strong molecular candidates underpinning the myogenic response in this vascular bed.