these changes that were evident 2 hr after the lesions were made included decreased cyclic amp levels in the heart , increased cgmp : camp ratio , camp phosphodiesterase ( 3':5'-camp 5'-nucleotidohydrolase , ec 3.1.4.17 ) and guanylyl cyclase ( gtp pyrophosphate-lyase ( cyclizing ) , ec 4.6.1.2 ) activities in the aorta and decreased snesitivity of adenylyl cyclase ( atp pyrophosphate-lyase ( cyclizing ) , ec 4.6.1.1 ) in both the aorta and heart to stimulation by the beta-adrenergic stimulant isoproterenol .
C0018358
guanylyl cyclase
C0024188
lyase