The perivascular adipose tissue (PVAT) regulates arterial tone. When comparing the effects of renal arterial PVAT on vasorelaxation response in SHRSP.Z-Lepr^fa/IzmDmcr rats (SPZF) and SHR/NDmcr-cp rats (CP), metabolic syndrome (MetS) model strains, enhanced acetylcholine-induced relaxation by PVAT was observed only in female CP. Furthermore, mRNA levels of apelin in PVAT are positively correlated with the enhancing effects of PVAT. MetS increases the risk of kidney dysfunction. Therefore, we investigated the relationship between apelin levels in renal arterial PVAT and kidney dysfunction in MetS model rats.
Male and female SPZF and CP aged 23 weeks were used. Systolic blood pressure (sBP) was measured using the tail-cuff method. Renal arterial PVAT was obtained from each rat, and mRNA transcript levels of apelin in the PVAT were examined by quantitative real-time polymerase chain reaction. Insulin, glucose, and creatinine in the serum and protein in the urine were measured using commercial kits. eGFR and HOMA-IR were calculated.
The highest apelin mRNA levels in PVAT and eGFR, while the lowest sBP, urine protein, and HOMA-IR levels were observed in female CP. Apelin mRNA levels in PVAT were not correlated with eGFR, urinary protein, sBP, and HOMA-IR levels.
This study suggests that apelin levels in PVAT are associated with PVAT-enhancing effects on vasorelaxation; however, the levels might not be directly affected by high blood pressure, insulin resistance, and kidney dysfunction in MetS.