Abstract
Renal blood flow is maintained within an appropriate range by autoregulation. One of its mechanisms is the tubulo-glomerula feedback, controlled by the juxtaglomerular apparatus located at the orifice of the glomerulus. There have been a few calcium visualisation studies with isolated nephron samples but has not been any in-vivo study. The purpose of this study is to visualise cellular calcium in association with the tubulo-glomerular feedback. We used Wistar rats (n=7) under anaesthesia. Fluo-4 and Texas Red conjugated albumin were administered prior to the experiment to visualise cellular calcium ions and intravascular space respectively. Glomerular microcirculation was visualised with a confocal microscope (Nikon A1R MP) after exposing the left kidney. To induce tubulo-glomerular feedback, salt solution in 25% concentration was administered (0.1 ml/kg/min) extrarenally. Afferent arterioles constricted and the calcium concentration at the vicinities of the juxtaglomerular apparatus increased 2 to 3 minutes after hypertonic salt administration (p<0.05). Saline administered as control caused none of above phenomena. Thus, we were able to visualise cellular calcium concentration change due to tubulo-glomerula feedback.
