Background: 

Many neuropeptides, like angiotensines and arginine-vasopressin, are involved in the regulation of bladder contractile activity. They activate the inositol-triphosphate way and increase intracellular calcium concentration.

Aim: 

To establish the effect of ghrelin and calcium chloride over amplitude and force of angiotensin and vasopressin-mediated contractions of detrusor organ strips from rat urinary bladder.

Materials and methods: 

Urinary bladders from Wistar rats, weighting 200-250 g were used. Obtained preparations were induced by angiotensin and vasopressin, independently and in combination with CaCl₂ or ghrelin.

Results: 

Angiotensin II (Ang II) and arginine-vasopressin (AVP) provoked contractile response with amplitudes 1.9 ± 0.2 g and 1.75 ± 0.12 g and maximal integral force (AUC)- 115.6 ± 20.7 gs and 761.29 ±113.3 gs, respectively. The presence of additional 10 mmol calcium in the enviroment led to increased amplitudes of nevropeptide-mediated contractions: for Ang II -2.18 ± 0.22 g and AVP-2.47 ± 0.4 g. Meanwhile the force of developed contraction was increased and maximum was reached with AVP- 1237.14 ±163.8 gs. Added 30 minutes in advance, ghrelin reduced the development of Ang II-mediated contractions to 0.87 ±0.2 g. Ghrelin did not affect over the amplitude of AVP-mediated contraction, but significantly lowered its integral force to 299.08 ±44.95 gs.

Conclusion: 

Our experimental data indicated that the increase of calcium in extracellular fluid has a synergistic effect over the neuropeptide mediated contraction`s force development in detrusor smooth muscle strips. Ghrelin antagonizes the contractile effect of Ang II and partially – of AVP.