Rats received a concomitant treatment with the selective beta(1)-adrenoceptor antagonist, bisoprolol (50 mg/kg/day p.o.) or were chronically pretreated with the selective << beta(2)-adrenoceptor >> agonist [[ salbutamol ]] (40 microg/kg/h) for 1 week to induce beta(2)-adrenoceptor desensitization.