Cardiac α₁‐adrenoceptor densities in different mammalian species

Abstract

1 ax-Adrenoceptor densities were studied in cardiac membrane preparations from several mammalian species including human failing hearts under identical experiment conditions; the al-adrenoceptor antagonist, [3H]-prazosin, was used as radioligand. End-stage heart failure (NYHA IV) in human hearts was due to idiopathic dilated cardiomyopathy. 2 The ventricular a1-adrenoceptor densities were not significantly different in guinea-pig, mouse, pig, calf, and man (11 to 18 fmol mg-' protein) but about 5 to 8 fold smaller than in rat (about 90 fmol mg-' protein). Right and left ventricular receptor densities were similar in these species. 3 A sufficient amount of right and left atrial tissue was obtained from rabbit, pig, calf, and man only. The a,-adrenoceptor densities in both atria of these species were found to be at the detection limit of the method used (less than 8 fmol mg-protein). 4 The equilibrium dissociation constant (KD) was similar in all species studied ranging from 0.047 + 0.006 to 0.063 ± 0.007 nmol 1'.5 It is concluded that differences in z1-adrenoceptor density between atria and ventricles may exist in mammalian species. The exceptionally high density of these receptors in rat ventricles seem to be a particular feature in these animals.

Effects of a Pure .ALPHA./.BETA.-Adrenergic Receptor Blocker on Monocrotaline-Induced Pulmonary Arterial Hypertension With Right Ventricular Hypertrophy in Rats

“…The number of cardiac α-and β-adrenergic receptors differs between rats and humans, 19,20 and such differences could have influenced the results of the present study. Therefore, we also need to examine the preventive effect of arotinolol in PAH patients.…”

Effects of loud noise exposure on mouse myocardium: A comparison with the rat

“…Although we already reported that noise exposure produces significant mitochondrial alterations in the rat myocardium (Soldani et al, 1997a,b), this is the first study investigating the effects of loud noise exposure on the mouse heart. This might be interesting, considering the similarities between mouse and human heart (Steinfath et al, 1992). The effects of noise exposure on mouse myocardium involve subcellular sites similar to those described in the rat (Paparelli et al, 1995;Pellegrini et al, 1996;Soldani et al, 1997a).…”

“…This higher sensitivity might be due to the zonal pattern of norepinephrine (NE) receptors (Gesi et al, 1999), which should be the final effectors for noise-induced myocardial alterations. In particular, rat myocardium possesses a high density of alpha-1 receptors in comparison with other mammalian species, such as mice or humans (Steinfath et al, 1992).…”

Cardiac Alpha1-Adrenergic Receptors: Novel Aspects of Expression, Signaling Mechanisms, Physiologic Function, and Clinical Importance

“…Interestingly, among most species, including mouse, guinea pig, rabbit, pig, and cow, heart a 1 -AR levels determined by ligand binding are relatively constant (mouse: mean of six studies, ;12 fmol/mg protein) (Steinfath et al, 1992a;Cavalli et al, 1997;Yang et al, 1998;Lin et al, 2001;O'Connell et al, 2003;Rokosh and Simpson, 2002), with the exception of rat heart, in which a 1 -AR levels are approximately 10-fold higher (rat: mean of four studies, ;114 fmol/mg) (Steinfath et al, 1992a;Michel et al, 1994;Noguchi et al, 1995;Stewart et al, 1994).…”