Aim: 

On example of vesical-preparations (guinea-pig) will be given recent/ earlier results concerning Ca-dependence of motor/electrical activities [Biomed.Techn. 39, 312-3/1994; Biophys. & Mol.Biol. 65/1, 170/1996; Proc. IUPS 14 (Budapest), 2428/1980; 17 (Helsinki) 529/1989; Faseb J. 19/4, A585/2005; Eur.J.Physiol. 443, S334/2002; 420, R99/1992; 419, R98/1991].

Method: 

Recording of motor/isometric and electrical/intracellular activity (see introd.).

Results: 

Spontaneous phasic detrusor-contractions (SPC): Detrusor-amplitudes (4.1 ± 2.4 mN=100%) after 3xCaCl₂ (normal 2.1 mM=1x, McEwen-solution) 101/111% (3/50 mN), frequency (4.0 ± 0.7/min=100%) 66.9/72.7% (3 mN/50 mN). Tonic trigonum-contractions (STC): Amplitudes (17.2 ± 11.6 mN=100%) changed after 3xCaCl₂ 82.5/133.6% (3/50 mN), frequency 65.8/18.7% (3/50 mN). After changed [CaCl₂] (0.1 to 3x) appeared different motor patterns incl. detrusor-SPC/STC (similar to trigonum). Ca-effect on electrical action potentials of vesical myocytes: Not only spike (S) activity was transformed into a burst-plateau (BP) one by stretch (3 to 80 mN), but also [CaCl₂]-reduction (0.5-0.1x) induced BP with increased frequency (reciprocal proportional to [CaCl₂]). Electro-induced detrusor-contractions (10Hz, 0.3ms, 3s) are strongly increased after stretch: Ca-increase had augmentory effects (110/130% 3/50 mN) (total n = 50).

Conclusion: 

Ca²⁺ participates essentially in electrical S-generation and S-transformation into BP probably via Ca-activated K-stretch-dependent channels: SPC could be related to electrical S- and STC to BP-activity. Further pharmacophysiological investigations could help for better pharmacological and electrotherapy of urinary bladder (incontinence, overactive bladder, etc.).