The lack of influence of some neuropeptides present in the posterior pituitary lobe on the frequency of spontaneous contraction of the isolated heart auricle.
Goraca. A A; Traczyk. W Z WZ
Key Findings
- A cardiodepressant factor from the posterior pituitary reduces heart auricle contraction frequency.
- Synthetic neuropeptides (substance P, leu‑enkephalin, met‑enkephalin, angiotensin II, arg‑vasopressin, oxytocin, delta sleep‑inducing peptide, atrial natriuretic factor) showed no effect on heart auricle beating in rats.
- The tested peptides likely have biological actions that differ from the cardiodepressant factor.
Practical Outcomes
- For DIY health enthusiasts, this study provides no actionable guidance on using these neuropeptides for heart or performance benefits. It simply confirms that, at the tested concentrations, these common peptides do not influence heart rhythm in this animal model.
Summary
Researchers tested several brain‑derived peptides (like substance P, enkephalins, vasopressin, oxytocin, etc.) on tiny heart pieces from newborn rats to see if they changed how fast the heart beats. None of the peptides altered the beating rate, meaning they act differently from a yet‑unknown heart‑depressing factor found in the pituitary.
Abstract
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 spontaneous contraction frequency of the isolated heart auricle of the following synthetic neuropeptides was determined: substance P, leu-enkephalin, met-enkephalin, 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 x 10(-7) to 1 x 10(-3) mol/l in the bathing medium and it was concluded that their biological properties differ from the cardiodepressant factor.
Study Information
pubmed
1990