The next property of life, which emerged specifically in multicellular organisms, was intercellular interactions – humoral and electrical, functioning as signals. The development of specialized areas sensitive to these signals – receptors, channels, and later synapses – marked a significant step. Nervous tissue, which in many higher organisms divides very little or not at all, devotes its entire resource to intercellular interactions – both electrical and chemical. Where mitosis is absent, electrogenesistakes precedence.
Much later, together with Professor A.M. Seledtsov, I co-authored an article for a student collection titled "Calcium Ions, cerebral paroxysms, epileptogenesis, mitosis, and apoptosis"[13]. At the time, we hypothesized that the calcium-calmodulin complex and nitric oxide are among the most ancient intracellular messengers. One of the most critical functions of calcium ion regulation in the nervous system is its role in apoptosis. Some effects of calcium ions on nervous tissue are temporally organized in a paroxysmal manner, primarily concerning pathological phenomena (epileptic paroxysms, the activation of pathological cravings for alcohol). Despite existing cellular calcium defenses, vertebrates – with their calcium-based skeletons – are prone to numerous pathological processes where hypercalcicity (an elevated concentration of calcium ions within the cell) plays a key role. These processes are temporally organized either paroxysmally (e.g., epileptic seizures, activation of alcohol cravings, certain cardiac arrhythmias) or non-paroxysmally (e.g., affective disorders, arterial hypertension).
We hypothesized that paroxysms in cases of hypercalcicity represent a process by which a cell (neuron) eliminates excitotoxicity, which would otherwise lead to apoptosis. This is most clearly observed in motor epileptic seizures. In such cases, the chemical energy of excitotoxicity is transformed into mechanical energy. The ease of this transformation is explained by the shared ontogenetic and phylogenetic origins of the nervous and locomotor systems. Specifically, in neurons, the calcium-calmodulin complex acts as a transformer of chemical energy into electrical energy, while in skeletal muscles, the calcium-troponin complex converts electrical energy into mechanical energy. In both cases, calcium ions and structurally similar proteins – calmodulin and troponin play a leading role in energy transformation. Sometimes, the epileptic mechanism only partially prevents apoptosis, and some neurons die. Clinically, this can manifest as Todd’s paralysis, a well-known phenomenon.