the k+-induced increase in developed tension observed in left atrial muscle preparations obtained from rat heart was not blocked by phentolamine and propranolol or by reserpine pretreatment but attenuated by stimulation at higher frequency , incubation at a lower temperature , or by veratridine , all of which have been shown to increase na+ loading of myocardial cells .
C0026845
muscle
C0225828
myocardial cells