see historic perspectives of medicine

• It was reported in 1960 that verapamil, a putative coronary vasodilator, possessed -ve inotropic & chronotropic effects not seen with nitrate vasodilators.
  • in 1967 it was suggested that this was due to decreased movement of Ca into cardiac myocytes;
• In 1969, it was shown there are 2 inwardly directed ionic currents that mediated atrial depolarisation:
  • fast Na channel (blocked by tetrodotoxin) & slow Ca channel;
• In 1972, gallopamil, a verapamil derivative, was shown to block the slow Ca channel;