To further study mechanisms of microvascular changes in uremia, heart tissue from mice with mild (n = 10) or severe uremia (n = 6) and controls (n = 13) was analyzed by RT-PCR for transcription levels of genes regulating angiogenesis: the transcription factor HIF-1α, the vascular endothelial growth factor VEGF-A and its receptor (KDR/Flk-1), the vascular growth factors angiopoietin 1 and 2 (Angpt-1, Angpt-2), their receptors TIE1 and TIE-2, and the matrix metalloproteinases 2 and 9 (MMP-2, MMP-9). Here, MMP9 is linked to uremia.