Introduction Pericytes are perivascular cells with multifunctional activities which are now being elucidated. Pericyte alteration or degeneration is linked directly with microangiopathy in diabetes, scleroderma and hypertension.

Aims The purpose of the present study is to investigate the pathologic changes of the myocardial capillary pericytes in hypertension with diabetes rats.

Methods The rat model of hypertensive with diabetes mellitus (SHDM) and the rat model of diabetes mellitus (DM) were induced by an intraperitoneal injection of streptozotocin combined with high fat diet in spontaneously hypertensive rats (SHR) and SD rats, respectively. The four groups were as follows: SD, DM, SHR and SHDM. The ultrastructure changes were examined by transmission electron microscope and the number of precity was assessed by immunohistochemistry of ventricular sections at 16 weeks.

Results Ultramicroscopic analysis of capillaries showed the pericytes on myocardial capillaries of SHR, DM, and SHDM were conspicuously abnormal in shape and were with cytoplasm containing abundant myofilament and organelle. In addition, pericytes seemed to be loosely associated with the endothelium. The number of pericytes in SHR, DM and SHDM were significantly increased than that in SD. The number of pericytes in SHDM were much higher than that in SHR (11.8±3.6 vs 3.9±1.1, p<0.01), but no significantly difference than that in DM (11.8±3.6 vs 10.2±3.3, p>0.05).

Conclusion These results suggest the phenotype changes and increase of myocardial capillary pericytes in response to hypertension with diabetes. These changes may contribute to arterialisations of myocardial capillary and pericapillary fibrosis.