Introduction:We have previously reported the expression of vascular endothelial growth factor A (VEGF-A) by podocytes and of VEGF receptor 2 by glomerular endothelial cells (GEnC), and described actions of VEGF-A on cultured GEnC. Recently we have described the expression of VEGF-C by podocytes. Aims: To define the expression of VEGFR3 in human GEnC, both in tissue sections and in culture, and investigate effects of its ligand, VEGF-C, on GEnC barrier properties. Methods: Renal cortex sections were examined by double labelling immunofluorescence to determine VEGFR3 localisation. Cultured GEnC were examined by confocal microscopy. Cell and glomerular lysates were analysed by Western blotting. GEnC monolayers were cultured on porous supports and the trans-endothelial electrical resistance (TEER, a measure of the integrity of cell monolayers) was recorded before and after treatment with 1 or 10nM VEGF-C. Alternatively the mutant VEGF-C₁₅₆S, a VEGFR3-specific agonist, or VEGF-A were used. Macromolecular permeability was assessed by labelled albumin flux across VEGF-C (10nM)-treated monolayers. Effects of VEGF-C and -A (both 1nM) on intracellular calcium ([Ca²⁺]_i) were measured by a Fura-2AM-based fluorescence technique. Results: VEGFR3 was expressed by GEnC in tissue sections and in culture where it exhibited a cell membrane distribution. VEGF-C dose-dependently increased TEER, with a maximal effect of 10nM VEGF-C at 120min of 6.8Ω(p≤0.01). VEGF-C₁₅₆S had no effect while VEGF-A reduced TEER as previously. VEGF-C reduced labelled albumin flux across GEnC monolayers by 32.8% (p≤0.05), corresponding to the observed increase in TEER. VEGF-C and VEGF-A caused 1.15- and 1.39-fold increases respectively in [Ca²⁺]_i(p<0.01). Conclusions: Expression of VEGFR3 on GEnC indicates the potential for signalling to GEnC through VEGF-C/VEGFR-3. VEGF-C has direct actions on GEnC, increasing monolayer integrity as measured by TEER and albumin passage, although VEGFR3 activation alone was not sufficient. Very few other mediators are known to increase endothelial integrity. This is in contrast to VEGF-A which reduces TEER of GEnC monolayers, an effect thought to be mediated through VEGFR2. Both VEGF-C and -A increased [Ca²⁺]_i, a change usually associated with an increase in permeability. These observations suggest that podocytes may exert precise control over GEnC phenotype, particularly with respect to barrier properties, via VEGF-C and a combination of VEGFR2 and 3, as well as through VEGF-A.