Biomedical subjects

B Eika

Publications and source records attributed to B Eika.

6 recordsLinked to original sources

PubMed1992

Collagen and bladder function in streptozotocin-diabetic rats: effects of insulin and aminoguanidine.

The effects of insulin (5 U/day subcutaneously for 60 days) and aminoguanidine (25 mg./kg./day via gavage for 60 days) on collagen concentration, resistance to enzymatic digestion with Pronase E, and the accumulation of advanced glycosylation end products in bladder tissue were studied in male streptozotocin-diabetic rats. The characteristic autofluorescence of glycosylated connective tissue was used to quantitate advanced glycosylation end products. Fluorescence was measured in digests of bladder tissue and expressed as fluorescence/micrograms. of hydroxyproline. Correlation to alterations in bladder function was made by studying in-vivo bladder micturition and in-vitro length-tension relations of bladder strips. Five groups of age-matched rats were studied: 1) controls, 2) controls treated with aminoguanidine, 3) diabetics, 4) diabetics treated with aminoguanidine, and 5) diabetics treated with insulin. The collagen concentration and the amount of collagen released by enzymatic digestion decreased while the connective tissue autofluorescence increased in bladders from diabetic rats. Insulin was able to prevent all of the observed changes while aminoguanidine protected against changes in accumulation of advanced glycosylation end products and resistance to enzymatic digestion but not against changes in collagen concentration. Stretchability of the bladder as measured by length-tension relations of bladder strips was inversely proportional to the amount of collagen, and therefore increased in diabetic rats. Diabetes of two months duration resulted in altered micturition pattern (increased fluid consumption, diuresis, micturition frequency, and average volume per micturition). Alterations in in-vivo and in-vitro bladder function were prevented by insulin treatment but not by aminoguanidine treatment. We have shown that the collagen component of the bladder wall changes in amount as well as in quality in the diabetic rat. Our data suggest that the amount, rather than the properties of collagen, is important for bladder function.

Animals↗

PubMed1992

Comparative autonomic responses of the cat and rabbit bladder and urethra.

The cat and the rabbit have both been utilized extensively in the study of lower urinary tract function. Previous studies have demonstrated that although both the cat and rabbit bladder are approximately the same weight, the in-vitro cat bladder can generate over 6 times the intravesical pressure of the rabbit bladder. The current study was designed to compare the ability of the isolated bladder to generate pressure with the pressures required to maintain flow through the isolated urethra for both the cat and the rabbit. The results can be summarized as follows. 1) The cat bladder is visibly much thicker than the rabbit bladder, and in vitro cystometry demonstrates that it is far less compliant than the rabbit bladder. 2) Over 20 cm.H2O pressure is required to begin flow through the isolated cat urethra preparation, whereas 5 cm.H2O begins flow through the rabbit urethra. 3) Increasing the flow rate (up to 7-fold) through both the isolated cat and rabbit urethra increases intraurethral pressure only slightly. 4) Both the isolated cat and rabbit urethra respond strongly to field stimulation and alpha-adrenergic stimulation (relative to the opening pressure required to begin flow), but not to cholinergic stimulation. 5) Field stimulation following pre-stimulation by methoxamine induces a strong relaxation of the pre-stimulated cat urethra, but an additive contraction in the pre-stimulated rabbit urethra. These studies demonstrate that in order for the cat to empty its bladder, it must generate a comparatively high intravesical pressure, whereas the rabbit is required to generate a relatively low intravesical pressure.

Animals↗

PubMed1992

Urinary bladder function in the tight-skin mouse.

Tight-skin mice develop hypertrophy of connective tissue and tendons, associated with increases in collagen concentration in skin, heart, lungs, and tail. The bladders from these mice have not previously been examined. Because of the purported importance of collagen in bladder wall structure and compliance, we examined collagen content, micturition characteristics, and length-tension relationships in bladders from tight-skin mice. Bladder collagen content and concentration were approximately 70% greater in 5-6 month tight-skin mice than age-matched controls, but bladder mass, protein content, and protein concentration were similar. Tight-skin mice urinated larger volumes more frequently during the light cycle, and the functional bladder capacity appeared to be greater than that of controls. There was a small shift to the right of the passive length-tension curves of bladder strips from tight-skin mice, but the shift was not statistically significant. The magnitude of active tension development was the same. The data suggest that bladder collagen concentration does not necessarily determine bladder capacity or compliance. It is suggested that other factors, such as the ratio of collagen subtypes or the collagen:elastin ratio may have more importance for the maintenance of bladder distension.

Animals↗

PubMed1992

Comparison of urinary bladder function in 6 and 24 month male and female rats.

Micturition characteristics, collagen composition, and in vitro urinary bladder strip contractility were examined in young adult (six month) and old (24 month) male and female Fischer 344 rats. Although young female rats consumed significantly less water than young males, there were no differences in volumes of urine excreted. Old females excreted significantly more urine than old males, but there were no differences in volumes of water consumed. Old male rats had similar micturition frequencies during the light and dark cycles, in contrast to females and young males, where the number of micturitions during the dark cycle was significantly greater than those during the light cycle. The mean and maximal micturition volumes were significantly greater in old males compared to young males and old females during both the light and dark cycles. Bladders from female rats weighed significantly less than bladders from males of the same age, and the bladders from young rats weighed less than those of old rats. The protein and collagen concentrations were significantly less in bladder bodies from young females than old females. The amount of collagen resistant to digestion by Pronase, and thus thought to be cross-linked, was significantly greater in bladders from old rats compared to young. No differences between groups were found in the contractile responses of bladder base strips. There were trends for the absolute contractile responses of bladder body strips from old males to field stimulation, carbachol, ATP, and KCl to be larger than the other groups, and for strips from the young females to be smaller. The responses of strips from young females to field stimulation and KCl were significantly less than those of young males or old females, and responses to 10(-3) M ATP were less than those of old females. Responses of strips from old males to 60 mM KCl were significantly greater than those of young males. The differences in contractility could be attributed to the differences in strip mass. It appears, therefore, that urinary bladder function in male and female rats is unaffected by increasing age between 6 and 24 months.

Adenosine Triphosphate↗

PubMed1991

A time-dependent study of passive esophageal wall properties and collagen content in rabbits with esophageal varices.

The passive biomechanical wall properties of the esophagus were studied in rabbits with esophageal varices and controls using a four-electrode impedance technique. Stepwise pressure inflation and deflation was done for analysis of esophageal cross-sectional area, compliance, and hysteresis monthly during six months. At sacrifice, the esophageal collagen content was determined. A small but statistically insignificant increase in compliance was observed during the six-month observation period in both groups. No differences were observed between the groups (P greater than 0.3). No change in hysteresis was observed in either group. The group with esophageal varices had significantly higher collagen content in the distal esophagus when compared to controls (P less than 0.05). No difference was demonstrated in the proximal part. No correlation was demonstrated between the collagen content and esophageal compliance. The study demonstrated that the method allows measurement of luminal cross-sectional area and tissue elasticity. No relationship was found, however, between the collagen content and compliance of the rabbit esophagus.

Animals↗

PubMed1990

Long-term observation of the detrusor smooth muscle in rats. Its relationship to ovariectomy and estrogen treatment.

We studied the bladders of 24-month-old intact rats, rats that had been ovariectomized at the age of 6 months, and intact and ovariectomized rats treated by estrogen from the age of 16 months. The study thus comprized four groups: group I: bilaterally ovariectomized rats; group II: intact rats; group III: ovariectomized rats treated with estrogen; group IV: intact rats treated with estrogen. The weight and collagen concentration of the bladders were determined. The ovariectomized bladders weighed significantly less and had a higher collagen concentration than the intact bladders. Estrogen substitution for ovariectomized rats reversed these parameters. Detrusor strips were also used for organ bath studies. All bladders were similar in regard to the nerve-mediated frequency-response relationship. The atropine-resistant response was studied by adding scopolamine to the organ bath. Strips from ovariectomized rats had a significantly diminished atropine-resistant response, which was abolished by estrogen substitution. The present study suggests that micturition problems in menopause might have a structural as well as a pharmacological explanation.

Animals↗