Increased number of cardiac adrenergic receptors following local heart irradiation.
The effect of local X irradiation on cardiac alpha and beta receptors was studied in Wistar rats. Animals were given local heart irradiation with single doses of 15 or 20 Gy and were examined after a range of latency times of 7 to 400 days. Using the radioactive ligands [3H]CGP-12177 and [3H]prazosin, the maximal binding capacity was determined from saturation experiments. At 7 days after 20 Gy the maximal binding capacity of both alpha and beta receptors was reduced to below the level of untreated control animals. Subsequently it rose continually to a maximum of 160% of the control level for beta receptors and 130% for alpha receptors at 400 days postirradiation. The antagonist affinity as judged from the dissociation constant for [3H]CGP 12177 and [3H]prazosin did not change significantly. A similar effect was observed after 15 Gy. An increase in adrenergic receptors may represent an important pathogenetic link between early morphological and late functional changes in the pathogenesis of radiation-induced heart disease.
Lauk
S
S
Institut für Strahlenbiologie, GSF, Neuherberg, Federal Republic of Germany.
Böhm
M
M
Feiler
G
G
Geist
B J
BJ
Erdmann
E
E
D000317:Adrenergic alpha-Antagonists / Q000378:metabolism; D000319:Adrenergic beta-Antagonists / Q000378:metabolism; D000818:Animals; D006321:Heart / Q000528:radiation effects*; D008297:Male; D011224:Prazosin / Q000378:metabolism; D011412:Propanolamines / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011942:Receptors, Adrenergic, alpha / Q000528:radiation effects*; D011943:Receptors, Adrenergic, beta / Q000528:radiation effects*; D014316:Tritium
D000317:Adrenergic alpha-Antagonists; D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011942:Receptors, Adrenergic, alpha; D011943:Receptors, Adrenergic, beta; D014316:Tritium; C033394:CGP 12177; D011224:Prazosin