Effects of verapamil, nifedipine, and dilazep on left ventricular relaxation in the conscious dog

Massimo Pagani, Paolo Pizzinelli, Raffaello Furlan, Stefano Guzzetti, Ornella Rimoldi, Giulia Sandrone

Research output: Contribution to journalArticlepeer-review


Summary: The cardiac systolic and diastolic effects of the two major calcium blockers, verapamil and nifedipine, were studied and compared with those produced by dilazep, a relatively new vasodilator with calcium blocking properties, in conscious instrumented dogs to avoid the complications of anaesthesia and recent surgery. Mean arterial pressure was reduced by nifedipine and dilazep but not by verapamil, whereas peak left ventricular pressure was reduced only by dilazep and verapamil. Consistent tachycardia occurred, the rate being highest with nifedipine and lowest with dilazep. Left ventricular dP/dt was unaffected by dilazep, reduced by verapamil, and increased by nifedipine; this increase was no longer observed after beta adrenergic blockade. Ventricular relaxation was assessed by calculating the time relaxation constant, tau. Verapamil increased tau significantly only after beta adrenergic blockade, whereas nifedipine and dilazep reduced it both before and after beta adrenergic blockade.These data suggest that reflex beta adrenergic mechanisms may modulate the effects of calcium blockade on both systolic and diastolic performance.

Original languageEnglish
Pages (from-to)55-64
Number of pages10
JournalCardiovascular Research
Issue number1
Publication statusPublished - Jan 1987


  • Calcium channel blockade
  • Conscious dog
  • Sympathetic reflexes
  • Systolic function
  • Ventricular relaxation

ASJC Scopus subject areas

  • Statistics, Probability and Uncertainty
  • Applied Mathematics
  • Physiology (medical)
  • Physiology
  • Cardiology and Cardiovascular Medicine


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