- Hypotonic filtrate (~100-200 mOsm/L)
- Reabsorption of Na+ and Cl- via thiazide-sensitive co-transporters.
- Ca2+ is reabsorbed.
- Basolateral Na+/K+ATPase antiporter absorbs Na+, secretes K+.
- pH: HCO3- is absorbed and H+ is secreted – or vice versa. This is in response to the acid/base state of the body.
- Parathyroid Hormone (PTH): acts here to reabsorb Ca2+ via phosphorylation of regulatory proteins. It enhances synthesis of all transporters in the DCT.
- Thiazide diuretics act here to inhibit Na+/Cl+ reabsorption by blocking their co-transporter. Increased ion excretion leads to increased H2O excretion, lending these medications their “diuretic” properties.
- Prostaglandins: released by cells of the macula densa in response to decrease in blood pressure. Acts on the afferent arterioles causing dilation and release of renin from their juxtaglomerular cells.
- Filtrate of varying osmolality and ion concentrations in response to the body’s current demands.