Figure 2.

Localization of the D1 DA receptor by subcellular fractionation. Rat renal outer cortical tissue slices were incubated with or without ANP (10⁻⁶ M) for 15 min, subjected to subcellular fractionation, and immunoblotted for D1 DA receptor. The amount of the integral membrane protein Na⁺,K⁺-ATPase, used as a marker for the plasma membrane, was highest in fraction 1 and not detectable in fractions 3–10 in vehicle-treated tissue. The plasma membrane fraction was therefore identified as fraction 1. In vehicle-treated tissue, the D1 DA receptor subtype was located mainly in fraction 7 (reference fraction).