Cardiac alpha 1-adrenoceptor densities in different mammalian species.
1. alpha 1-Adrenoceptor densities were studied in cardiac membrane preparations from several mammalian species including human failing hearts under identical experiment conditions; the alpha 1-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 alpha 1-adrenoceptor densities were not significantly different in guinea-pig, mouse, pig, calf, and man (11 to 18 fmol mg-1 protein) but about 5 to 8 fold smaller than in rat (about 90 fmol mg-1 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 alpha 1-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-1 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 l-1. 5. It is concluded that differences in alpha 1-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.
Steinfath
M
M
Abteilung Allgemeine Pharmakologie, Universitäts-Krankenhaus Eppendorf, Universität Hamburg, Germany.
Chen
Y Y
YY
Lavický
J
J
Magnussen
O
O
Nose
M
M
Rosswag
S
S
Schmitz
W
W
Scholz
H
H
D000818:Animals; D001665:Binding Sites; D002311:Cardiomyopathy, Dilated / Q000378:metabolism*; D006168:Guinea Pigs; D006325:Heart Atria / Q000378:metabolism; D006352:Heart Ventricles / Q000378:metabolism; D006801:Humans; D008297:Male; D009206:Myocardium / Q000378:metabolism*; D011224:Prazosin / Q000378:metabolism; D011817:Rabbits; D051381:Rats; D017208:Rats, Wistar; D011942:Receptors, Adrenergic, alpha / Q000378:metabolism*; D013045:Species Specificity; D013552:Swine
D011942:Receptors, Adrenergic, alpha; D011224:Prazosin