Key result
Anterior canine LV walls exhibit ~89% greater beta-adrenoceptor binding than inferior walls.
Why the study?
Differences in myocardial beta-adrenoceptor binding between anterior and inferior left ventricular walls may explain regional autonomic response heterogeneity in the heart.
Answers are grounded in this paper and cite their sources.
Regional beta-adrenoceptor heterogeneity in canine LV is hypothesis-generating; leaves open relevance to human disease or therapy.
Myocardial beta-adrenoceptor binding was investigated, with (-)3H dihydroalprenolol as radioligand, in microsomes derived from anterior (ALV) and inferior (ILV) myocardial wall sections of the canine left ventricle. Characterisation of specific binding sites revealed a hierarchy of myocardial beta-adrenoceptor binding with greater binding occurring to the anterior than the inferior wall of the left ventricle, under identical experimental conditions. Equilibrium analysis by Scatchard plots suggested a significant (P less than 0.01) difference in the number of receptors (Bmax ALV = 70 fmol . mg-1 protein vs Bmax ILV = 37 fmol . mg-1 protein) with no alteration in the binding affinity of the receptors (KDALV = 10.1 nmol . litre-1 vs KDILV = 6.7 nmol . litre-1). Such differences in the extent of binding of beta-adrenoreceptors in cardiac muscle may be of physiological and pathological significance and may account for the heterogeneity of regional autonomic responses in the heart.
No takes yet. Share an insight, caveat, or question.
Burnam et al. (1981) studied Normal canine left ventricle. Anterior myocardial wall (ALV) microsomes vs. Inferior myocardial wall (ILV) microsomes was evaluated on Number of receptors (Bmax) (p=<0.01). Beta-adrenoceptor binding was significantly greater in the anterior compared to the inferior wall of the canine left ventricle (70 vs 37 fmol/mg protein, P<0.01), with no alteration in binding affinity.
Synapse has enriched 10 related papers. Consider them for comparative context: