Supersensitivity to carbachol in the parasympathetically decentralized feline urinary bladder

We investigated the concentration-response relations for carbachol, the morphological characteristics and the mechanical properties of feline detrusor strips from 1) normal cats, cats subjected to 2) parasympathetic sacral decentralization, 3) urinary diversion followed by parasympathetic sacral decentralization and 4) urinary diversion only. Hypertrophy of the detrusor and supersensitivity to carbachol (a decrease of EC50) were found only after parasympathetic decentralization. No hypertrophy developed and no change in the EC50-value for carbachol was found if urinary diversion preceded the parasympathetic decentralization. A decreased ability of force production per unit cross sectional smooth muscle area was found in the decentralized bladders compared to the controls. However, the total ability of force production and hence also pressure production of the decentralized bladders would be expected to be enhanced due to a 4 to 5-fold increase of bladder weight (mainly muscle mass). No differences in the active length-tension relations were found in the 4 groups. It is suggested that parasympathetic decentralization per se does not give rise to detrusor hypertrophy or increased sensitivity to carbachol. Provided that the situation in man is comparable to that in the cat, it might be that the supersensitivity test a.m. Lapides-Glahn reflects the presence of detrusor hypertrophy rather than the presence of a neurogenic lesion.