Angiotensin II (Ang II) induces marked, dynamic increases in the permeability of the glomerular filtration barrier (GFB) in rats. After binding to its receptor, Ang II elicits Ca2+ influx into cells, mediated by TRPC5 and TRPC6 (transient receptor potential canonical type 5 and 6). Clemizole and La3+ salts have been shown to block TRPC channels in vitro, and we therefore tested their potential effect on Ang II-induced glomerular hyperpermeability. Anesthetized male Sprague-Dawley rats were infused with Ang II (80 ng kg–1min–1) alone, or together with clemizole or low-dose La3+ (activates TRPC5, blocks TRPC6) or high-dose La3+ (blocks both TRPC5 and TRPC6). Plasma and urine samples were taken during baseline and at 5 min after the start of the infusions and analyzed by high-performance size-exclusion chromatography for determination of glomerular sieving coefficients for Ficoll 10–80 Å (1–8 nm). Ang II infusion evoked glomerular hyperpermeability to large Ficolls (50–80 Å), which was ameliorated by clemizole, having no significant effect on glomerular filtration rate (GFR) or Ang II-mediated increase in mean arterial pressure (ΔMAP). In contrast, high- and low-dose La3+ significantly lowered ΔMAP and reduced Ang II-induced hyperpermeability. Combined, clemizole and low-dose La3+ were less effective at ameliorating Ang II-induced glomerular hyperpermeability than low-dose La3+ alone. In conclusion, our data show that both clemizole and La3+ are effective against Ang II-induced glomerular hyperpermeability, with differential effects on blood pressure. Further research using more specific blockers of TRPC5 and TRPC6 should be performed to reveal the underlying mechanisms.