Novel therapeutic approaches of Sildenafil against rhabdomyolysis-associated acute kidney injury

Objectives: Rhabdomyolysis-associated acute kidney injury (AKI) is a manifestation frequently observed in many cases. Sildenafil (Sild) is a phosphodiesterase-5 inhibitor selected in this study for its experimental protective effects in muscle and kidney injury experimental models. The current study aimed to hypothesize that Sild had a renoprotective effect through the anti-oxidant, anti-inflammatory, and anti-apoptotic mechanisms in glycerol (Gly)-induced rhabdomyolysis rat model. Methods: Male Sprague Dawley rats were allocated into four groups: control group (saline, i.p); Sild control group (5 mg/kg, orally); glycerol (Gly) group (50%, 10 ml/kg, i.m.); prophylactic Sild plus glycerol group (5 mg/kg, orally, 1 hr before glycerol). All treatments were applied as a single dose. Blood samples and renal tissues were collected 24 hr following glycerol injection. Results: Gly produced renal morphological changes, muscle, and renal dysfunction, in addition to increased mortality rates, oxidative stress, renal inflammatory responses, and renal apoptosis. Sild reduced muscle/kidney function disturbances (serum total CK, CK-MB, creatinine, BUN, in addition to urinary creatinine levels), reduced oxidative stress in renal tissue, increased antioxidant defense (TAC, SOD, NRF-2/HO-1), decreased mortality rates, and accelerated renal histological recovery. Additionally, inflammatory mediator levels of TNF-α, NF-κB, and COX-2 were suppressed. Moreover, the study revealed new insights into protection from rhabdomyolysis-associated AKI, through reduction of renal apoptosis by decreasing levels of BAX and increasing levels of BCL-2. Conclusions: Sild protected against rhabdomyolysis-linked renal morphological damage, renal and muscle function disturbances, by decreasing renal oxidative stress, inflammation, and apoptosis. Therefore, Sild proved its muscle/reno-protective impacts, and possibly can be used as a new therapeutic approach for acute muscle and kidney injuries, which represents a new benefit for a common and widely used medication.