Effect of Pregnancy on Rabbit Urinary Bladder Physiology

Abstract

Recent advances in imaging technology have allowed for the diagnosis of many congenital urologic abnormalities through the use of antenatal ultrasonography. There is controversy in the literature as to whether antenatally detected dilatations of the urinary tract are always secondary to obstruction or if in select cases the dilatations are physiologic in nature and will spontaneously regress. Benign dilatations of the fetal urinary tract are postulated to be secondary to the increased fetal diuresis and a more compliant fetal urinary tract. No one has investigated the possibility that such dilatations might be a consequence of the hormonal changes seen with pregnancy. In this study we present evidence for a change in bladder function with pregnancy. A summary of our results shows that in the presence of bethanechol, strips from the urinary bladders of pregnant rabbits generate 50% less tension in response to calcium than those from nonpregnant rabbits. Such a suppression in smooth muscle function might also help explain the benign dilatations of the upper urinary tract which are seen frequently during pregnancy.

The effect of pregnancy and contractile activity on bladder muscarinic receptor subtypes

“…These changes include an increase in residual volume, decrease in bladder tone, and increase in urinary stress incontinence. It may be possible to extrapolate our findings of decreased bladder muscarinic receptors in the gravid rabbit and the previously detailed decreased muscarinic contractile response [Zderic et al, 1990a;Levin et al, 1991] to human pregnancy. Therefore, the hormonal effects of pregnancy cause an equal decrease of both bladder muscarinic receptor subtypes, rather than one subtype, and this may be partly responsible for the clinical urologic findings seen in human pregnancy.…”

Pharmacology of the Lower Urinary Tract: Basis for Current and Future Treatments of Urinary Incontinence

“…Thus, in the presence of bethanechol, bladder strips from pregnant rabbits generated 50% less tension in response to calcium than those from nonpregnant rabbits (Zderic et al, 1990). The isolated whole bladder from pregnant animals responded to low-frequency stimulation and to ATP with a greater increase in intravesical pressure than did preparations from virgin rabbits, whereas the response to bethanechol was greater in the virgin rabbits (Levin et al, 1991).…”

Developmental Factors in the Contractile Response of the Rabbit Bladder to Both Autonomic and Non-Autonomic Agents

“…One end of the tissue was suspended by a silk suture to a Grass transducer. Transducers were cali brated using a 5-gram weight, and then the tissues were all stretched to 150% of their starting length (the length at which maximum active tension is generated) [6], All tissues were allowed to equilibrate for 1 h at this length. Dose response curves were generated for bethanechol.…”