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Previous in vivo studies indicate that 2-hydroxyestradiol (2OHE) attenuates cardiovascular and renal diseases. In vitro studies suggest that the biological effects of 2OHE are mediated by 2-methoxyestradiol (2MEOE) after methylation of 2OHE by catechol-O-methyltransferase (COMT). This study tested the hypothesis that in vivo 2OHE is a prodrug of 2MEOE. We administered to male rats i.v. boluses of either 2OHE or 2MEOE and measured plasma levels of 2OHE and 2MEOE by gas chromatography-mass spectrometry at various time points after drug administration. After administration of 2OHE, plasma levels of 2OHE declined extremely rapidly [t 1/2(1) ϭ 0.94 min and t 1/2(2) ϭ 10.2 min] becoming undetectable after 45 min. Concomitant with the disappearance of 2OHE, 2MEOE occurred and then declined [t 1/2(1) ϭ 7.9 min and t 1/2(2) ϭ 24.9 min]. The peak concentration and total exposure (area under the curve) for 2OHE were much lower than for 2MEOE. 2OHE had a much higher plasma clearance (CL) and volume of distribution (V d ) compared with 2MEOE (2OHE: CL ϭ 1215 ml min Ϫ1 kg Ϫ1 and V d ϭ 17,875 ml/kg; 2MEOE: CL ϭ 50 ml min Ϫ1 kg Ϫ1 and V d ϭ 1760 ml/kg). After administration of 2MEOE, plasma levels of 2MEOE declined [t 1/2(1) ϭ 2.5 min and t 1/2(2) ϭ 20.2 min] with a plasma CL of 50 ml min Ϫ1 kg Ϫ1 and a V d of 1500 ml/kg. We could not detect 2OHE in plasma from rats receiving 2MEOE. We conclude that the conversion of 2OHE to 2MEOE is so efficient that in terms of 2MEOE exposure, administration of 2OHE is bioequivalent to administration of 2MEOE itself.2-Hydroxyestradiol (2OHE) is a metabolite of estradiol with low affinity for estrogen receptors (Ball and Knuppen, 1990). Our in vivo work demonstrates that 2OHE attenuates the development of obesity, the metabolic syndrome, and vascular and renal dysfunction in obese ZSF1 rats (Tofovic et al., 2001). Moreover, our more recent studies indicate that 2OHE protects against puromycin aminonucleoside-induced nephropathy (Tofovic et al., 2002), monocrotaline-induced pulmonary hypertension (Tofovic et al., 2003b), and angiotensin II-induced renal and cardiovascular injury (Tofovic et al., 2003a).Although the aforementioned in vivo studies were conducted with 2OHE, in point-of-fact 2OHE is readily oxidized and is therefore a poor candidate for drug development. 2-Methoxyestradiol (2MEOE), on the other hand, is less susceptible to oxidation, and in vitro evidence suggests that most of the cellular effects of 2OHE are mediated by 2MEOE, a metabolite of 2OHE that is devoid of estrogenic activity. In this regard, inhibition of catechol-O-methyltransferase (COMT), the enzyme that methylates 2OHE and converts it to 2MEOE, blocks the ability of 2OHE to inhibit growth of vascular smooth muscle cells (Dubey et al., 2000), cardiac fibroblasts (Dubey et al., 2002b), and renal mesangial cells (Dubey et al., 2002a). Moreover, 2OHE inhibits vascular smooth muscle cell growth in cells obtained from wild-type mice but not in cells cultured from COMT knockout mice (Zacharia et al., 2003b). In cont...

This article describes preliminary in vivo studies evaluating the osteogeneic potential of bone morphogenetic proteins (BMPs) delivered from an absorbable puttylike polymer matrix. In the first study, bovine-derived bone morphogenetic proteins were incorporated in an polymer matrix consisting of 50:50 poly(DL-lactide-co-glycolide) dissolved in N-methyl-2-pyrrolidone. The matrix was implanted in an 8 mm critical-size calvarial defect created in the skull of adult Sprague-Dawley rats (n = 5 per treatment group). After 28 days, the implant sites were removed and examined for new bone formation, polymer degradation, and tissue reaction. Gamma-irradiated polymer matrices appeared to give more bone formation than nonirradiated samples (histological analysis; 2. 76 + 1.34 mm(2) of bone versus 1.30 + 0.90 mm(2) of bone, respectively and x-ray analysis; 27.2 + 15.9 mm(2) of bone versus 20. 7 + 16.7 mm(2) of bone, respectively) and less residual polymer (0.0 + 0.0 versus 0.2 + 0.4, respectively). The polymer implants with bone morphogenetic protein also gave less inflammatory response than the polymer controls (gamma irradiated polymer/BMP = 1.8 + 0.4 and nonirradiated polymer/BMP = 1.2 + 0.4 versus polymer only = 3.0 + 1. 2, respectively). However, despite trends in both the x-ray and histological data there was no statistical difference in the amount of new bone formed among the four treatment groups (P > 0.05). This was most likely due to the large variance in the data scatter and the small number of animals per group. In the second animal study, bovine-derived BMPs and the polymeric carrier were gamma irradiated separately, at doses of 1.5 or 2.5 Mrad, and their ability to form bone in a rat skull onlay model was evaluated using Sprague-Dawley rats (n = 5 per treatment group). Histomorphometry of skull caps harvested 28 days after implantation showed no significant differences as compared to non-irradiated samples, in implant area, new bone area, and percent new bone (P > 0.05). These results suggest gamma irradiation may be useful in sterilization of the bovine-derived BMPs and the polymeric carrier for potential bone repair and/or regeneration applications.

Sodium may contribute to the pathogenesis of hypertension by impairing arterial baroreceptor reflex function. The objectives of this study were to 1) determine whether a high sodium diet depresses arterial baroreceptor reflex function in normotensive humans, and 2) determine whether alterations in baroreceptor reflex function are related to changes in arterial compliance. Seventeen normotensive men, aged 30 ±2 years, received 10 and 200 meq sodium per day diets, each for 5 days, in a randomized crossover trial. Carotid baroreceptor reflex function was assessed by measuring the blood pressure response to sequential neck suction (0, -10, -20, and -30 mm Hg) and neck pressure (0, +10, +20, and +30 mm Hg). Forearm vascular resistance was determined by venous occlusion plethysmography. Arterial compliance was evaluated by calculating the quotient of the diastolic blood pressure decay time constant and forearm vascular resistance. Blood pressure averaged 124±3/62±2 mm Hg on the low sodium diet and 122±3/60±2 mm Hg on the high sodium diet (p-NS). Baroreceptor reflex slopes representing the systolic and diastolic blood pressure responses to changes in neck chamber pressure were steeper in the subjects when randomly assigned to low sodium diet than to high sodium diet Diastolic blood pressure decay time and forearm arterial compliance were similar during low and high sodium intake. We conclude that short-term exposure to a high sodium diet depresses carotid baroreceptor reflex function in normotensive humans. This observation cannot be attributed to changes in the arterial compliance. (Hypertension 1991; 17:989-996)