Slow after hyperpolarisation

Slow After Hyperpolarisation (sAHP) refers to a prolonged period of hyperpolarisation in a neuron or cardiomyocyte following an action potential or other depolarising spike. In neural circuitry, a train of action potentials may be required to induce a sAHP; this is unlike fast AHPs which require no more than a single action potential. sAHPs are due to an extended potassium flux via calcium activated potassium channels (IKCa). The resulting hyperpolarisation lasts for several seconds in a sAHP and effectively inhibits neural activity for this period. Fast and Medium AHPs have shorter periods.