REN and Hypertension: Since hypertension and hyperactivity of the renin-angiotensin-aldosterone system (RAAS) are considered as risk factors for the development of chemotherapy-induced HF [21,22,23,24]), the study was performed in Ren-2 transgenic rats (TGR), in which endogenous activation of the RAAS and hypertension are combined [33] Moreover, to gain a better insight into the possible role of potential compensatory activation of systemic and intrarenal neurohormonal systems, plasma and kidney concentrations of catecholamines, angiotensin II (ANG II), and angiotensin 1-7 (ANG 1-7) were determined.