Atrial natriuretic peptide receptors are present in brown adipose tissue

Binding activities and metabolic effects of atrial natriuretic peptide (ANP) were examined in rat brown fat. ANP binding sites were identified in thin sections of brown adipose. Binding of [125I]-ANP to brown fat membranes was specific, saturable and time-dependent. A single class of high affinity sites (Kd, 1.7 nM; Bmax, 226 fmol/mg protein) was present. ANP increased cGMP synthesis in isolated cells (EC50, 2.5 x 10(-9) M), but did not alter epinephrine-stimulated glycerol production. The results demonstrate the presence of specific ANP receptors in brown fat, activation of which increases cGMP formation; however, since neither ANP nor cGMP affect lipolysis, the biological importance of these receptors remains unknown.