Maryrose P Sullivan

Effect of angiotensin II on corpus cavernosum smooth muscle in relation to nitric oxide environment: in vitro studies in canines.

In extracavernosal vascular tissue, smooth muscle tone is modulated by a balance between angiotensin II (Ang II) and nitric oxide (NO). We hypothesized that these substances also play an important role in regulating cavernosal smooth muscle contractility. We therefore studied the in vitro effects of an Ang II receptor antagonist and a nitric oxide synthase (NOS) inhibitor on the contractile effects of Ang II, phenylephrine, and electrical field stimulation in canine corpus cavernosum. Ang II caused a dose-dependent contraction of cavernosal smooth muscle which was inhibited by the Ang II receptor antagonist and augmented by NOS inhibition. Contractions induced by phenylephrine or electrical stimulation were diminished by the Ang II receptor antagonist, and augmented by NOS inhibition. We conclude that Ang II plays an important role in modulating cavernosal smooth muscle tone, and that the contractile effect of Ang II on cavernosal tissue is modulated by the local NO environment.

THE MAXIMUM WATTS FACTOR AS A MEASURE OF DETRUSOR CONTRACTILITY INDEPENDENT OF OUTLET RESISTANCE

The maximum watts factor (WFmax) is often used to characterize detrusor contractility. It was recently shown that the WFmax may increase in some patients with chronic outlet obstruction. It is, however, unclear whether this increase reflects a dependence of the WFmax on the degree of outlet obstruction or whether it represents a true increase in detrusor contractility secondary to chronic outlet obstruction. Therefore, this study was performed to investigate this issue using a canine model of acute outlet obstruction.

Combinations of maximum urinary flow rate and American Urological Association symptom index that are more specific for identifying obstructive and non-obstructive prostatism

Uroflowmetry and the American Urological Association symptom index (AUASI) are often used clinically to evaluate patients with benign prostatic hyperplasia (BPH). Since results from these tests may be used to determine a treatment course, including surgical intervention, we investigated if specific combinations of uroflowmetry and AUASI parameters could better predict urodynamically confirmed prostatic obstruction.

Detrusor internal and external work in relation to passive urethral resistance in a canine model of the lower urinary tract

This study was conducted to evaluate whether passive urethral resistance, detrusor internal work, and detrusor external work are independent measures of the voiding process. Passive urethral resistance, detrusor internal work, detrusor external work, and detrusor total work of 5 canines were determined under nonobstructive and obstructive outlet conditions. All urodynamic analyses were performed on a surgically exposed urinary tract. Solid‐state pressure transducers were used to measure the intravesical and distal urethral pressures, while an ultrasonic flow meter was used to obtain a simultaneous measure of urinary flow rate. Detrusor contractions were induced using bilateral electrical stimulation of the pelvic nerves. Varying degrees of outlet obstruction were created using an inflatable sphincter cuff secured around the proximal urethra. Urethral resistance, internal work, and total work increased with increasing obstruction, while external work decreased with increasing obstruction. Internal work was linearly and negatively correlated to external work. At low degrees of obstruction, internal and external work changed more rapidly than passive urethral resistance per unit change in obstruction. As obstruction was increased, the change in work parameters per unit change in obstruction decreased, while the change in passive urethral resistance per unit change in obstruction increased. Our results indicate that at low degrees of outlet obstruction (cuff volume <60% of isometric cuff volume), detrusor internal and external work are more sensitive to changes in obstruction than passive urethral resistance. It therefore appears prudent to use these work parameters with a passive urethral ???.