<prompt> The factormechanism involved in glomerulotubular balance is:signalling by macula densa cellsOncotic pressure in peritubular capillariesContraction of the mesangial cellsSluggish blood flow in medullary interstitium  <response>: G-T balance refers to the mechanism by which increase in GFR and filtration of Na propoionately increases the Na and water reabsorption. Thus, a constant fraction 67 of the filtered Na and water is reabsorbed from PCT, despite fluctuations in GFR. Mechanism: Increased GFR and increased filtered load of Na water a increased protein concentration in the glomerular capillary plasma as the fluid has been filtered out of this plasma Protein-rich plasma leaves the glomerular capillaries efferent aerioles and enters the peritubular capillaries Colloid Oncotic pressure will increase in peritubular capillaries a increased the solute and water reabsorption by the PCT. Options A C are involved in tubuloglomerular feedback. Sluggish blood flow in medullary interstitium is the basis for countercurrent exchange by vasa recta. 