The lack of influence of some neuropeptides present in the posterior pituitary lobe on the frequency of spontaneous contraction of the isolated heart auricle

Gorąca A., Traczyk W. Z.: The lack of influence of some neuropeptides present in the posterior pituitary lobe on the frequncy of spontaneous contraction of the sisolated heart auricle. Acta Physiol. Pol. 1940, 4 (6): Investigations have shown the presence of a cardiodepressant factor in the fluid incubating the posterior pituitary lobe “in situ”, which decreased contraction frequency of the isolated heart auricle (Acta Physiol. Pol., 1984, 35: 460-468). The influence on the spontaneuos contraction frequency of the isolated heart auricle of the following synthetic neuropeptides was determined: substance P, leu-enkephalin, met-enke- phalin, angiotensin II, arg-vasopressin, oxytocin, delta sleep-inducing peptide and atrial natriuretic factor. It was found that the investigated neuropeptides had no effect on the contraction frequency of the isolated auricle of the heart right atrium of two-day-old rat in a concentration from 2.1 × 10⁻⁷ to 1 × 10⁻³ mol/1 in the bathing medium and it was concluded that their biological properties differ from the cardiodepressant factor.