ISSN:
1440-1681
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Medicine
Notes:
1. Triiodothyronine (T3; 1.0 mg/kg per day subcutaneously) was administered to 10 dogs for 14 days; 10 saline-treated dogs served as controls. T3-treated dogs showed the expected physiological responses of hyperthyroidism; further, chronotropic responses to isoprenaline in vivo were significantly increased in T3-treated dogs.2. β-Adrenoceptor subtype density was measured in membrane preparations by displacement of l25I-iodocyanopindolol binding by the selective β2-adrenoceptor antagonist, ICI 118, 551. T3 treatment led to a 93% increase in right atrial β1-adrenoceptor density and a 141% increase in left ventricular β1-adrenoceptor density; β2-adrenoceptor densities in right atrial, left ventricular and lung membranes were unchanged.3. T3-treatment did not change basal or maximally stimulated adenylate cyclase activities in left ventricular membranes.4. Thus, the cardiovascular changes in experimental hyperthyroidism in dogs were accompanied by an increased chronotropic response in vivo to isoprenaline and an increased β1-adrenoceptor density in atrial and ventricular membranes. However, there was no corresponding change in basal or maximal responsiveness of adenylate cyclase in ventricular membranes.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1440-1681.1992.tb00413.x
