Altered beta-receptor responsiveness in uraemic rats.

Beta-receptor responsiveness was evaluated in 24-hour nephrectomised rats. Heart rate responses following intravenous isoproterenol injections into conscious uraemic (n = 9) and sham operated controls (n = 7) were measured. These preliminary results indicate that heart rate at rest and after blockade of the autonomic nervous system was slower in uraemic rats. Blood pressure before and after autonomic blockade was not different between groups, Maximal heart rate increase following intravenous isoproterenol was significantly less pronounced in uraemic than 0.05). The blood pressure decreasing effect of intravenous isoproterenol was enhanced in the nephrectomised group (p less than 0.01).