PROFILE OF β‐ADRENOCEPTORS IN FEMORAL, SUPERIOR MESENTERIC AND RENAL VASCULAR BEDS OF DOGS

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Abstract
The homogeneity of β‐adrenoceptors in femoral, superior mesenteric and renal vascular beds was investigated by the use of the regional perfusion technique in dogs. Isoprenaline and salbutamol produced dose‐related increases in femoral and superior mesenteric blood flow. The dose‐response curves for the two agonists were parallel, but salbutamol was approximately 1/15 as potent as isoprenaline on a weight basis. Isoprenaline and salbutamol increased renal blood flow in a dose‐related manner. However, salbutamol was approximately 1/240 as potent as isoprenaline on a weight basis, and the slope of the dose‐response curve for salbutamol was less steep than that for isoprenaline. The dose‐response curves to isoprenaline for increase in femoral and superior mesenteric blood flow were shifted to the right by intravenous pindolol but not by intravenous or intra‐arterial practolol. The dose‐response curves to isoprenaline for increase in renal bood flow were shifted to the right more markedly by intravenous pindolol than by intravenous or intra‐arterial practolol. The results indicate that β‐adrenoceptors of the renal vascular bed consist of β1‐type and β2‐type whereas the femoral and superior mesenteric vascular beds contain only β2‐adrenoceptors.