Lucien Rizzo

Receive:

• Hypotonic filtrate (~100-200 mOsm/L)

Process:

• 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. 

Produce:

• 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. 

Export:

• Filtrate of varying osmolality and ion concentrations in response to the body’s current demands.