Respiratory effects of the paratrigeminal area activation in rats

A very important aspect of breathing control problem in mammals is studying mechanisms, which mediate respiratory activity of the paratrigeminal area (PA) of the pons. Objective. The purpose of the study is to analyze the changes in external respiration and diaphragm reactions to electrical stimulation and L-glutamate activation into PA in rats. Materials and Methods. Acute experiments were performed on rats anesthetized with urethane (n=15). PA was irritated with a pulse current by means of unipolar steel needle-shaped microelectrode. L-glutamate solution (10-7 M, 0.2 μl) was injected into PA through a glass micro-cannula (microsyringe MSh-1). External respiration was registered by means of spirography; diaphragm response was estimated using electromyogram (EMG). Results. PA activation by electrical stimulation and L-glutamate microinjection caused similar effects in the form of pulmonary ventilation reduction and respiratory rate reduction due to prolongation of the expiratory phase. Changes in the breathing pattern corresponded to increased intervals between the inspiratory volleys on the EMG of the diaphragm. Conclusion. The data obtained indicate that PA plays an important part in the rhythm and breathing pattern regulation of mammals. PA involvement in respiratory control is mediated by glutamatergic bonds. In rats, such bonds are included in the mechanisms regulating the duration of the exhalation and, thus, respiratory rate.