Beta-adrenoceptors in human tracheal smooth muscle: characteristics of binding and relaxation

Life Sci. 1987 Jun 29;40(26):2561-70. doi: 10.1016/0024-3205(87)90079-8.

Abstract

Specific binding of [125I]-(-)-cyanopindolol to human tracheal smooth muscle membranes was saturable, stereo-selective and of high affinity (Kd = 5.3 +/- 0.9 pmol/l and RT = 78 +/- 7 fmol/g tissue). The beta 1-selective antagonists atenolol and LK 203-030 inhibited specific [125I]-(-)-cyanopindolol binding according to a one binding site model with low affinity in nearly all subjects, pointing to a homogeneous beta 2-adrenoceptor population. In one subject using LK 203-030 a small beta 1-adrenoceptor subpopulation could be demonstrated. The beta-mimetics isoprenaline, fenoterol, salbutamol and terbutaline recognized high and low affinity agonist binding sites. Isoprenaline's pKH- and pKL-values for the high and low affinity sites were 8.0 +/- 0.2 and 5.9 +/- 0.3 respectively. In functional experiments isoprenaline relaxed tracheal smooth muscle strips having intrinsic tone with a pD2-value of 6.63 +/- 0.19.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Atenolol / metabolism
  • Binding, Competitive
  • Humans
  • In Vitro Techniques
  • Muscle Contraction*
  • Muscle Relaxation*
  • Muscle, Smooth / metabolism*
  • Pindolol / analogs & derivatives
  • Pindolol / metabolism
  • Propranolol / metabolism
  • Receptors, Adrenergic, beta / metabolism*
  • Receptors, Adrenergic, beta / physiology
  • Sarcolemma / metabolism
  • Stereoisomerism
  • Trachea / metabolism*
  • Trachea / physiology

Substances

  • Receptors, Adrenergic, beta
  • cyanopindolol
  • Atenolol
  • Propranolol
  • Pindolol