Glomeruli or interstitium targeted by inter-renal injections supplemented by electroporation: Still a useful tool in renal research. 
Studies concerning proteins are always a crucial part of renal research.  As a result of current technologies, scientists have mastered several techniques for generating genetically modified animals.  However, in most cases, accessing these animals is still time-consuming and often expensive.  This makes the alteration of protein expression by in vivo plasmid transfection an easily-accessible alternative.  However, there is still no comprehensive study describing where plasmids would be expressed when they are injected into the kidneys.  We injected pEGFP-N1 into rats via intra-/inter-renal channels and detected green fluorescent protein (GFP) by immunohistochemistry and immunofluorescence to localize plasmid expression.  Seven days post-injection, we found that GFP was expressed in the glomeruli when pEGFP-N1 was injected via the renal artery or vein enhanced by electroporation and in the interstitium following injection via the ureter.  Other channels, including intraperitoneal, subcapsule and parenchymal injection, only led to scattered expression within the kidneys.  The present study provides evidence that plasmid transfection via the renal vessels is suitable for glomeruli research and that transfection via the ureter is appropriate for studies regarding interstitium lesions.  Additionally, we provide evidence that plasmid transfection on live animals is still an applicable and useful tool, as well as being cost-effective and facile.