What happens when too much sodium flows in the cell due to a faulty voltage-gated sensor? What about too little?

Question

The activation gate opens, signaling depolarization. Eventually, the inactivation gate closes, ending depolarization and beginning repolarization.

What is the physiological impact of the inactivation gate remaining open too long, letting in too much sodium into the cell than a normal action potential? This would raise the magnitude of the action potential.

What would be the impact if it remained open for too short a time?

Answer 1

To answer the OP directly: You may be interested in looking at diseases that abnormally increase or decrease the activity of sodium channel proteins, changing the degree to which sodium ions cross the cell membrane. Some diseases are genetic in basis, which means they are inherited. This lends them to characterization and study.

This review paper by George summarizes some of the genetic diseases associated with sodium channel mutations, which might give you some direction for further research:

1. Muscle sodium channelopathies (SCN4A)
   • Hyperkalemic periodic paralysis
   • Paramyotonia congenita
   • Potassium-aggravated myotonia
   • Painful congenital myotonia
   • Myasthenic syndrome
   • Hypokalemic periodic paralysis type 2
   • Malignant hyperthermia susceptibility
2. Cardiac sodium channelopathies (SCN5A)
   • Congenital long QT syndrome (Romano-Ward)
   • Idiopathic ventricular fibrillation (Brugada syndrome)
   • Isolated cardiac conduction system disease
   • Atrial standstill
   • Congenital sick sinus syndrome
   • Sudden infant death syndrome
   • Dilated cardiomyopathy, conduction disorder, arrythmia
3. Brain sodium channelopathies (SCN1A, SCN2A, SCN1B)
   • Generalized epilepsy with febrile seizures plus
   • Severe myoclonic epilepsy of infancy (Dravet syndrome)
   • Intractable childhood epilepsy with frequent generalized tonic-clonic seizures
   • Benign familial neonatal-infantile seizures
4. Peripheral nerve sodium channelopathies (SCN9A)
   • Familial primary erythermalgia

Generally, you might search on the term "sodium channel mutant" or "mutations" to see what kinds of health problems are caused by under- or over-activity of these proteins.