Serum concentrations of estriol vary widely after application of vaginal oestriol cream.

AIMS: The aim of this study was to establish the pharmacokinetic profile of serum oestriol (E3 ) concentrations over 24 h following application of vaginal E3 in chronic users (>12 weeks of E3 use). The interindividual and intraindividual differences before and after E3 were examined. METHODS: Ten women participated. Vaginal cream was omitted for ≥36 h prior to the study days. Blood sampling was performed for E3 , oestradiol and oestrone concentrations prior to cream application and at 1, 2, 3, 5, 8, 10, 12 and 24 h afterwards. In five women, all samples were repeated on a separate day. RESULTS: E3 was absorbed rapidly in most women. Peak serum E3 concentration occurred around 2 h (range 1-5 h). The decline in E3 concentrations was also rapid: falling <100 pmol L-1 in six out of ten women within 8 h and returning to ≤ 10 pmol L-1 at 24 h in nine out of the ten patients. Interindividual variability for peak concentrations was considerable (mean 546 pmol L-1 ; 95% CI 349-743). Area under the concentration-time curve (AUC) values over a dosage interval also varied widely: mean 2145 pmol.h L-1 ; 95% CI 1422-3233. However, repeated measurements in the same woman were highly (peaks: ρ = 0.94) or moderately (AUC: P = 0.74) correlated. CONCLUSIONS: Postmenopausal E3 concentrations are negligible. Serum E3 concentrations of chronic users of E3 cream varied greatly; however, concentrations declined rapidly within 8 h, generally reaching 'postmenopausal' levels by 24 h. The basis for the variation between subjects needs further elucidation. Additional research is required to establish the safety of topical E3 .

Expression and localization of pannexin-1 and CALHM1 in porcine bladder and their involvement in modulating ATP release.

ATP release from urinary bladder is vital for afferent signaling. The aims of this study were to localize calcium homeostasis modulator 1 (CALHM1) and pannexin-1 expression and to determine their involvement in mediating ATP release in the bladder. To determine gene expression and cellular distribution, PCR and immunohistochemistry were performed, respectively, in the porcine bladder. CALHM1 and pannexin-1-mediated ATP release in response to hypotonic solution (0.45% NaCl)-induced stretch, and extracellular Ca2+ depletion ([Ca2+]0) was measured in isolated urothelial, suburothelial, and detrusor muscle cells. CALHM1 and pannexin-1 mRNA and immunoreactivity were detected in urothelial, suburothelial, and detrusor muscle layers, with the highest expression on urothelium. Hypotonic stretch caused a 2.7-fold rise in ATP release from all three cell populations (P < 0.01), which was significantly attenuated by the pannexin-1 inhibitor, 10Panx1, and by the CALHM1 antibody. Brefeldin A, a vesicular transport inhibitor, and ruthenium red, a nonselective CALHM1 channel blocker, also significantly inhibited stretch-mediated ATP release from urothelial cells. [Ca2+]0 caused a marked, but transient, elevation of extracellular ATP level in all three cell populations. CALHM1 antibody and ruthenium red inhibited [Ca2+]0-induced ATP release from urothelial cells, but their effects on suburothelial and detrusor cells were insignificant. 10Panx1 showed no significant inhibition of [Ca2+]0-induced ATP release in any types of cells. The results presented here provide compelling evidence that pannexin-1 and CALHM1, which are densely expressed in the porcine bladder, function as ATP release channels in response to bladder distension. Modulation of extracellular Ca2+ may also regulate ATP release in the porcine bladder through voltage-gated CALHM1 ion channels.