Role of nitric oxide and cyclooxygenase products in controlling vascular tone in uterine microvessels of rats.

The importance of nitric oxide (NO) and dilator prostaglandins in uterine resistance arterioles was investigated. In pentobarbital anaesthetized rats at dioestrus-2, the uterine microcirculation in vivo was transilluminated by a fibreoptic probe and microvessels (circumferential arterioles) viewed by video microscopy. Arteriolar diameters were measured while increasing concentrations of acetylcholine (ACh), serotonin (5-HT), phenylephrine (PE), or angiotensin II (AII) were applied topically (suffused) over the uterus. Agonists were applied alone or with ibuprofen (IBU; cyclooxygenase inhibitor), N omega-nitro-L-arginine (L-NA; nitric oxide synthase inhibitor) or both. Circumferential arterioles were dilated by ACh and 5-HT (10(-8)-10(-4) mol l-1) and constricted by PE (10(-8)-10(-5) mol l-1) and AII (10(-11)-10(-7) mol l-1). Suffusion of L-NA or L-NA with ibuprofen (10(-4) mol l-1 each) abolished ACh-induced dilation; ibuprofen alone blocked dilation at higher ACh concentrations. Serotonin-induced relaxation was significantly attenuated by L-NA alone or in combination with ibuprofen. Vasoconstriction induced by PE was enhanced by L-NA alone and L-NA with ibuprofen, but ibuprofen alone had no effect. In contrast, AII-induced constriction was enhanced significantly by ibuprofen or L-NA and further enhanced when both ibuprofen and L-NA were present. These results suggest that ACh can release either nitric oxide (NO) or cyclooxygenase products to cause uterine arteriolar dilation and that 5-HT-induced uterine microvascular relaxation is mediated via NO only. They also suggest that PE-induced vasoconstriction is attenuated by the release of NO but not cyclooxygenase products and that constrictor responses evoked by AII are attenuated by both NO and dilator prostaglandin release. Thus, both nitric oxide and dilator prostaglandins are important in the control of uterine microvessels.

A new technique for studying the uterine microvasculature in the rat.

OBJECTIVE: Our purpose was to develop a method for direct measurement of rat uterine microvessels and to test their viability. STUDY DESIGN: In anesthetized female Sprague-Dawley diestrus rats, one uterine hom was isolated from the body cavity with its nerve and blood supply intact. A small fiberoptic probe inserted into the lumen of the uterus served as a light source for transillumination of uterine vessels. Diameters of circumferential arterioles were observed while increasing concentrations of vasoactive agonists were suffused over the uterus. RESULTS: No significant diameter changes occurred in circumferential arterioles of the control group (100-minute suffusion of Krebs solution). Dilation with papaverine (100 mumol/L) demonstrated that vessels possessed basal tone. Circumferential arterioles showed concentration-dependent constriction to phenylephrine and angiotensin II and dilation to acetylcholine and serotonin. CONCLUSIONS: This uterine microcirculatory preparation provides a stable, reproducible model of a unique microcirculatory bed that responds to vasoactive agents in a manner similar to other microcirculatory beds.

The nutritional adequacy of a limited vegan diet for a Controlled Ecological Life-Support System.

Purdue University, as well as the Johnson and Kennedy Space Centers and NASA Ames Research Center, are investigating approximately 5-10 plants that will be grown hydroponically to provide not only the energy and nutrients, but also the oxygen for humans habitating in Mars and lunar bases. The growth and nutritional status of rats fed either a control diet (adequate in all macro- and micronutrients) or a strict vegetarian diet consisting of 5 (vegan-5) or 10 (vegan-10) candidate crop species were investigated. In addition, vegan-10 diets were supplemented with mineral and/or vitamin mix at a level similar to the control diets to assess the effect of supplementation on nutrient status. The assessment of inedible plant material as an alternative food source was also investigated. Results of this study demonstrated that consumption of the vegan-10 diet significantly improved weight gain of rats compared to that for rats fed the vegan-5 diet. Mineral supplementation, at a level present in the control diet, to the vegan-10 diet improved growth and nutrient status, but growth was significantly lower compared to the control-fed rats. Inclusion of inedible plant material, high in ash content, improved some indices of nutrient status, without improving growth.

Compositional and toxicological evaluation of the diazotrophic cyanobacterium, Cyanothece sp. strain ATCC 51142.

Compositional analyses of Cyanothece sp. strain ATCC 51142 showed high protein (50-60%) and low fat (0.4-1%) content, and the ability to synthesize vitamin B12. The amino acid profile indicated that Cyanothece sp. was a balanced protein source. Fatty acids of the 18:3n-3 type were also present. Mineral analyses indicated that the cellular biomass may be a good source of Fe, Zn and Na. Caloric content was 4.5 to 5.1 kcal g dry weight-1 and the carbon content was approximately 40% on a dry weight basis. Nitrogen content was 8 to 9% on a dry weight basis and total nucleic acids were 1.3% on a dry weight basis. Short-term feeding studies in rats followed by histopathology found no toxicity or dietary incompatibility problems. The level of uric acid and allantoin in urine and tissues was low, suggesting no excess of nucleic acids, as sometimes reported in the past for a cyanobacteria-containing diet. The current work discusses the potential implications of these results for human nutrition applications.