This post is showing the sodium transport coupled with the transport of the lactate ion in the apical membrane of the S1 segment of the proximal tubule. Monocarboxylates like L-lactate, propionate, butyrate, or nicotinate can be cotransported with sodium

• The Na/K ATPase, which brings 2 potassium ions into the cell and releases 3 sodium ions into the interstitial space.
• The sodium/lactate cotransporter (SMCT2) at the apical membrane, which brings in 2 sodium ions from the filtrate together with 1 lactate ion.

This will be shown again in a future post when urate transport is reviewed. It will also be reviewed when SMCT1 is shown in the S3 segment of the proximal tubule

Previous Posts in this Series

Renal Tubular Transport #1. S1 Segment, Proximal Tubule. Sodium Transport 1

Renal Tubular Transport #2. S1 Segment, Proximal Tubule. Sodium Transport 2

Renal Tubular Transport #3. S1 Segment, Proximal Tubule. Sodium Transport 3

Renal Tubular Transport #4. S1 Segment, Proximal Tubule. Sodium Transport 4

Renal Tubular Transport #5. S1 Segment, Proximal Tubule. Sodium Transport 5