Antti Talo

Phasic non-micturition contractions in the bladder of the anaesthetized and awake rat

To characterize the contractile activity that occurs in the bladder during the filling phase of the micturition cycle (non‐micturition contractions, NMCs), which generate transient rises in intravesical pressure not associated with urine flow.

The role of the rhabdosphincter in female rat voiding

To obtain information on the mechanisms of female rat micturition using a model in which pressure was measured in the bladder and distal part of the urethra corresponding to the location of the rhabdosphincter, providing information on the role of the sphincter in opening and closing the urethral lumen.

Transmitters contributing to the voiding contraction in female rats.

To assess in detail the contribution of acetylcholine and ATP to the different phases of the voiding contraction, urine flow and rhabdosphincter electromyographic (RB‐EMG) activity in rats, using α,β‐methylene‐ATP (desensitizing purinoceptors) and atropine (blocking muscarinic receptors). These agents and possibly other transmitters contribute to bladder emptying in rats, but how they contribute to the different phases of the micturition cycle, including the intraluminal pressure high‐frequency oscillations (IPHFOs) is unclear.

A dose-dependent dual effect of oestrogen on voiding in the male mouse?

To explore the effect of different degrees of oestrogenization on male voiding, by treating adult castrated and 5α‐dihydrotestosterone (DHT)‐maintained male mice with different doses of oestrogens, as exposure of male mice to excessive amounts of oestrogens can cause bladder outlet obstruction (BOO); in addition, male mice lacking oestrogen receptor (ER)α (ERKO) or ERβ (BERKO) were studied to assess the importance of ER subtypes.

Possible action of the proximal rhabdosphincter muscle in micturition of the adult male rat.

Micturition requires high bladder pressure and simultaneous opening of the urethra. In adult male rat, a rhabdosphincter (RB) is known to be electrically active when the bladder pressure is high. This indicates a closure rather than an opening of the urethra, which is inconsistent with the requirements of optimal urodynamics. In order to solve this problem, we simultaneously recorded electromyogram (EMG) of the proximal RB, bladder pressure, and flow rate. Micturition was evoked by an increased volume of saline in the bladder. A computer‐based recording device was used with minimal filtering. The EMG was recorded with a monopolar flexible suction electrode. The suction electrode records action potentials resembling those obtained with a microelectrode technique. During the early high‐frequency intraluminal pressure oscillation period (IPHFO), the increase of pressure initially associated with a decrease of potential of the RB. When the first flow peak appeared, the relationship of the bladder pressure and RB single EMG activities changed. The increasing pressure coincided with the positive potential wave (depolarisation). It was interrupted by a transient negative polarity period called transient repolarisation (TRP) coinciding with a flow rate peak, thus indicating an opening of the RB lumen. After the TRP, the depolarisation continued. Additional experiments employing different methods are needed for positive identification of the TRP mechanism. Neurourol. Urodynam. 20:197–213, 2001.

NONTRAUMATIC URETHRAL DYSSYNERGIA IN NEONATALLY ESTROGENIZED MALE RATS

PURPOSEnBladder outlet obstruction develops in estrogen treated males. Because of the lack of electromyography recordings, earlier studies have not clarified the failure mechanisms of voiding. We simultaneously recorded electromyography activity of the proximal rhabdosphincter in neonatally estrogenized rats with transvesical cystometry and urethral flow, followed by morphometric analysis of the urethral structure.nnnMATERIALS AND METHODSnRats treated neonatally with 10 microg. diethylstilbestrol daily on days 1 to 5 after birth were used in urodynamics and morphological studies at ages 5 to 6.5 months. Using anesthesia the bladder, anterior surface of the proximal rhabdosphincter and distal urethra were exposed to record simultaneously the high frequency oscillations of intraluminal bladder pressure, and the rates of intermittent flow from the distal urethra and electromyography activity of the proximal rhabdosphincter with a suction electrode.nnnRESULTSnNeonatally estrogenized rats had higher mean maximal bladder pressure plus or minus standard deviation (42.1 +/- 6.4 versus 37.7 +/- 4.9 mm. Hg, p = 0.01), decreased mean flow (2.3 +/- 0.1 versus 4.1 +/- 1.6 ml. per minute, p < 0.0001) and mean increment of proximal rhabdosphincter electromyography depolarization amplitude (3.0 +/- 0.78 versus 2.6 +/- 0.87 mV., p = 0.02) compared with controls, while mean transient repolarization was absent or highly decreased (-0.3 +/- 0.61 versus 0.3 +/- 0.9 mV., p = 0.04). Morphologically the proximal rhabdosphincter was atrophied with increased connective tissue.nnnCONCLUSIONSnAlterations in the structure and electromyography activity of the urethral musculature imply that neonatal exposure to diethylstilbestrol predisposes male rats to urethral atrophy and dyssynergia, evident as altered electromyography activity of the proximal rhabdosphincter.

Temperature acclimation of the perch Perc fluviatilis L.): Changes in duration of cardiac action potential

Abstract 1. 1. Temperature acclimation for the duration of transmembrane action potential (AP) of heart ventricle was studied in vitro in the perch in winter, spring and autumn when the animals were acclimated to 2–6°C, but acclimated in the laboratory to 5 and 16°C up to 5 weeks. 2. 2. Warm acclimation caused shortening of the AP at high temperatures. Acclimation was of Prossers type III, rotation with an intersecting point at about 7°C. In warm acclimated fish the temperature dependency was greater than in cold acclimated fish. 3. 3. Warm acclimation shown in the duration of the AP was more pronounced in winter and spring than in autumn. 4. 4. It is concluded that the annual rhythm of the physiological state of eurythermic fish is an important factor for temperature acclimation.

DEVELOPMENTAL, ESTROGEN INDUCED INFRAVESICAL OBSTRUCTION IS REVERSIBLE IN ADULT MALE RODENTS

PURPOSEnWe treat neonatally estrogenized rats and aromatase over expressing AROM+ male mice with infravesical obstruction using the specific aromatase inhibitors finrozole and letrozole, and analyzed whether developmentally induced alterations in urodynamics and rhabdosphincter are reversible in adulthood.nnnMATERIALS AND METHODSnAdult estrogenized rats and AROM+ mice were treated with aromatase inhibitors for 6 weeks. Maximal and mean bladder pressure, the urinary flow rates and electromyography activity were recorded from the proximal rhabdosphincter. In addition, proximal rhabdosphincter thickness in the AROM+ mouse was measured and correlated with seminal vesicle size and serum testosterone concentrations.nnnRESULTSnFinrozole and/or letrozole treatment significantly increased the mean maximal flow rate plus or minus SD in AROM+ mice (4.7 +/- 2.0 versus 13.3 +/- 4.4 ml. per minute, p = 0.0004) and in estrogenized rats (18.4 +/- 6.18 versus 31.1 +/- 10.85 ml. per minute for finrozole p = 0.005) and 32.4 +/- 14.3 for letrozole, p = 0.005), while bladder pressure slightly decreased. The reappearance of transient repolarization, indicating urethral lumen opening, coincided with an increased flow rate on electromyography in the proximal rhabdosphincter in rats. Relative thickness of the proximal rhabdosphincter (p = 0.007), seminal vesicle size (p = 0.0002) and mean serum testosterone concentration (472.5 +/- 230.35 versus 3,065.6 +/- 1,994.67 pg./ml., p = 0.0002) were restored after finrozole treatment in AROM+ mice.nnnCONCLUSIONSnCurrent findings indicate that alterations in urodynamics, seminal vesicle size, and rhabdosphincter size and function in developmentally estrogenized male rodents are reversible when treated with aromatase inhibitor.

Biochemical Properties of OR-1259 - A Positive Inotropic and Vasodilatory Compound with an Antiarrhythmic Effect

OR-1259 is a positive inotropic and vasodilatory compound with antiarrhythmic properties. Biochemically, OR-1259 can act as a troponin modifier, as an phosphodiesterase III inhibitor and as an inhibitor of voltage-sensitive Ca2+ current.

Electrical activity in the human oviduct after the menopause

Electrical activity was recorded in 18 morphologically normal human oviducts excised from 17 women during hysterectomy. All women were in the first five years after menopause. The first part of the oviduct to become inactive after menopause was the isthmus near the uterus or the ampullary-isthmic junction. The region which exhibited electrical activity last was the ovarian end of the tube. The typical wave-form of electrical activity in post-menopausal oviducts resembled that recorded during the follicular phase in fertile women: a single smooth wave lasting 3-5s. In three cases, over a bulbous swelling of the ampulla, this typical activity was replaced in continuous, high frequency activity. A hypothesis is provided that the observed changes in electrical activity may be related to certain clinical phenomena such as the increased incidence of tubal pregnancy in the pre-menopause.