DENERVATION-INDUCED CHANGES IN ALPHA-ADRENERGIC AND BETA-ADRENERGIC RECEPTORS OF THE RAT SUB-MANDIBULAR GLAND

  • 1 January 1979
    • journal article
    • research article
    • Vol. 211  (2) , 394-400
Abstract
Denervation resulted in a marked increase in the .beta.-adrenergic response and isoproterenol-stimulated cyclic AMP accumulation of dispersed cells prepared from a rat submandibular gland. The increase in .beta.-adrenergic response was paralleled by an increase in the density of .beta.-adrenergic receptors in membranes prepared from these glands. Denervation also produced a moderate increase in .alpha.-adrenergic receptor density in membranes prepared from whole glands. The .alpha.-adrenergic response in cells, epinephrine-induced release of K, appeared unaltered by denervation. Membranes prepared from denervated dispersed cells did not show the increase in .alpha.-adrenergic receptor density seen in membranes from an intact denervated gland. Apparently the removal of noradrenergic nerve terminals affects .alpha.- and .beta.-adrenergic receptors differently. While it is clear that .beta.-adrenergic membrane receptors participate in denervation-induced supersensitivity, the changes in .alpha.-adrenergic membrane receptors are more complex and may not contribute to the supersensitivity seen after denervation. On the basis of competitive binding studies, the adrenergic receptors in membranes from intact submandibular glands were subclassified as .beta.-1 and .alpha.-2. Denervation did not alter the binding characteristics of the .alpha.-2 receptors in this gland, demonstrating that .alpha.-2 adrenergic membrane receptors can be postsynaptic in this adrenergically innervated tissue.