Beata Modzelewska

Apamin inhibits NO-induced relaxation of the spontaneous contractile activity of the myometrium from non-pregnant women

There is now considerable evidence for the involvement of K+ channels in nitric oxide (NO) induced relaxation of smooth muscles including the myometrium. In order to assess whether apamin-sensitive K+ channels play a role in NO – induced relaxation of the human uterus, we have studied the effect of specific blockers of these channels on the relaxation of myometrium from non-pregnant women. In vitro isometric contractions were recorded in uterine tissues from non-pregnant premenopausal women who had undergone hysterectomy. Apamin (10 nM) and scyllatoxin (10 nM) did not alter spontaneous myometrial contractions. However, 15-min pretreatment of the myometrium strips with apamin completely inhibited relaxation caused by diethylamine-nitric oxide (DEA/NO). The pretreatment with scyllatoxin significantly reduced (about 2.6 times) maximum relaxation of the strips induced by DEA/NO (p < 0.05). These results strongly suggest that, beside Ca2+ and voltage dependent charybdotoxin-sensitive (CTX-sensitive) K+ channels, apamin-sensitive K+ channels are also present in the human non-pregnant myometrium. These channels offer an additional target in the development of new tocolytic agents.

Cu(II) complexation does not affect oxytocin action on pregnant human myometrium in vitro

OBJECTIVE Copper may influence the in vivo and in vitro uterine activity. Recent evidence shows that cupric ions can easily form complexes with oligopeptides like oxytocin (OXT). The high complex stability in vitro suggests a possibility of complex formation in vivo. STUDY DESIGN In vitro isometric contractions were recorded in uterine tissues from pregnant women undergoing caesarean sections and the effect of OXT and the Cu-OXT complex on isolated human pregnant myometrium was investigated. RESULTS In the concentration range from 10(-14) to 10(-6)M of OXT alone, pre-formed Cu-OXT complex, and OXT following sample preincubation with Cu(II) salt, nosignificant differences were observed for the following parameters of pregnant uterine smooth muscle contraction: the area under the curve, frequency and amplitude of contraction. CONCLUSION The binding of Cu(2+) ions does not abolish the ability of OXT to interact with oxytocin receptors and stimulate myometrial contraction in vitro.

Congenital vesicouterine fistulas-A PRISMA-compliant systematic review

Vesicouterine fistulas (VUFs) are infrequent abnormal connections between the bladder and the uterine cavity or cervical canal, being mainly sequelae of repeat Cesarean sections. Exceedingly rare are congenital VUFs. This is a systematic review of available world data aimed to characterize congenital VUFs and better understand the mechanism(s) of their formation.

Altered uterine contractility in response to β-adrenoceptor agonists in ovarian cancer

We aimed to prospectively examine β-adrenoceptor-mediated uterine contractility in women suffering from gynecological malignancies. Myometrial specimens were obtained from non-pregnant women undergoing hysterectomy for benign gynecological disorders, and ovarian, endometrial, synchronous ovarian–endometrial, and cervical cancer. Contractions of myometrial strips in an organ bath before and after cumulative dosages of β2- and β3-adrenoceptor agonists with preincubation of propranolol, SR 59230A, and butoxamine were studied. All agonists induced a dose-dependent attenuation for uterine contractility in endometrial or cervical cancer, similar to that observed in the reference group. Contradictory effects were observed for ovarian cancer alone or in combination with endometrial cancer. CL 316243 or ritodrine abolished the relaxation, whereas BRL 37344 increased the uterine contractility in ovarian cancer. Moreover, β-adrenoceptor antagonists caused varied effects for β2- or β3-adrenoceptor agonists. Our experiments demonstrate that ovarian cancer, alone or as synchronous ovarian–endometrial cancer, substantially alters uterine contractility in response to β-adrenoceptor agonists.

Levels of l-ascorbic acid and cadmium in the saphenous vein of patients with coronary artery disease are negatively correlated

BACKGROUND The aim of this study was the simultaneous determination of levels of cadmium and l-ascorbic Acid (AA) in human saphenous vein (SV) used in coronary artery bypass grafting (CABG) and check whether there is a relationship between these levels. METHODS Human SV were collected from 40 patients (20 men and 20 women; age, 40-75 years) at the time of routine coronary artery surgical revascularization. The concentration of cadmium in the tissue was determined according to the GF AAS-atomic absorption method. The concentration of AA was assayed in supernatant by FIA method with spectrophotometric detection. RESULTS AA concentration (mean±SD); men: 98,7±13,18μg/g tissue, women: 96,06±11,98μg/g tissue. Cadmium concentration(mean±SD); men: 309±103,71ng/g tissue, women: 348,5±255,71ng/g tissue. Correlations among concentrations of AA and cadmium were insignificant negative in the group of men (Pearson r=-0,1504, p=0,5269) and in the group women (Pearson r=-0339, p=0144). CONCLUSIONS Negative correlations among concentrations of AA and cadmium in human SV obtained in our study may indicate a protective effect of this vitamin in relation to toxic cadmium.

The Assessment of a Selective Inhibition of Potassium Channels and Guanylate Cyclase in the Relaxation Induced by Exogenous Nitric Oxide in the Human Nonpregnant Myometrium

Abstract To evaluate the involvement K+ channels in the relaxation induced by exogenous nitric oxide, after preincubation with L-arginine analogue L-NA in the human nonpregnant myometrium. The activity of myometrial strips, obtained from 60 premenopausal hysterectomised women, mounted in an organ bath was recorded under isometric conditions using force transducers with digital output. Concentration-response curves to DEA/NO after inhibition of endogenous NO were constructed in the absence and presence of soluble granulate cyclase and K+ channels’ blockers. The responses were quantified by calculating the area under the curve, the amplitude and frequency of the contractions. The inhibition of NOS results in slight but significant attenuation of the myometrium strips response to DEA/NO. Pre-treatment with both sGC inhibitors after preincubation with L-NA did not counteract the DEA-NOinduced relaxation of the spontaneous contractions of the myometrial strips. Application of blockers of different types of K+ channels to the myometrial strips significantly attenuated relaxing effect of cumulative DEA/NO administration in all cases. The present data indicate that even when endogenous production of NO is inhibited, the DEA/NO induced relaxation of human non-pregnant myometrium without involving the cGMP pathway.