BACKGROUND: The kidney is an important organ for maintaining blood pressure. We have previously reported that transplanted metanephroi can reproduce some kidney functions. The aim of the present study was to determine the metabolic function of transplanted metanephroi with particular reference to maintaining blood pressure. METHODS: Male Wistar rats were transplanted with metanephroi (transplanted group, n = 28), following unilateral nephrectomy. For comparison, we performed unilateral nephrectomy without transplantation in 32 rats (non-transplanted group, n = 18; haeminephrectomy control group, n = 14). The remaining kidney was removed 2 weeks after the initial operation, while control rats had a sham operation. Hypotension was induced by intravenous infusion of diltiazem hydrochloride or rapid withdrawal of blood. Mean arterial blood pressure (MAP) was invasively monitored and plasma renin activity (PRA) was analysed at multiple time points. Renin expression by metanephroi was evaluated by real-time polymerase chain reaction and immunohistochemistry. RESULTS: Metanephroi in the transplanted group expressed renin messenger RNA. Metanephros transplantation significantly raised PRA and maintained MAP compared with the non-transplanted group. No significant differences between the transplanted and control groups were found with respect to PRA or MAP. PRA was positively correlated with metanephroi weight as well as MAP in the transplanted group. CONCLUSION: The present study shows that transplantation of metanephroi produces PRA and contributes to raising MAP in a rat model of acute hypotension.
BACKGROUND: The kidney is an important organ for maintaining blood pressure. We have previously reported that transplanted metanephroi can reproduce some kidney functions. The aim of the present study was to determine the metabolic function of transplanted metanephroi with particular reference to maintaining blood pressure. METHODS: Male Wistar rats were transplanted with metanephroi (transplanted group, n = 28), following unilateral nephrectomy. For comparison, we performed unilateral nephrectomy without transplantation in 32 rats (non-transplanted group, n = 18; haeminephrectomy control group, n = 14). The remaining kidney was removed 2 weeks after the initial operation, while control rats had a sham operation. Hypotension was induced by intravenous infusion of diltiazem hydrochloride or rapid withdrawal of blood. Mean arterial blood pressure (MAP) was invasively monitored and plasma renin activity (PRA) was analysed at multiple time points. Renin expression by metanephroi was evaluated by real-time polymerase chain reaction and immunohistochemistry. RESULTS: Metanephroi in the transplanted group expressed renin messenger RNA. Metanephros transplantation significantly raised PRA and maintained MAP compared with the non-transplanted group. No significant differences between the transplanted and control groups were found with respect to PRA or MAP. PRA was positively correlated with metanephroi weight as well as MAP in the transplanted group. CONCLUSION: The present study shows that transplantation of metanephroi produces PRA and contributes to raising MAP in a rat model of acute hypotension.