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Biomedical subjects

G N Smith

Publications and source records attributed to G N Smith.

148 records · Page 9Linked to original sources
PubMedDate not supplied

Carbon monoxide decreases perfusion pressure in isolated human placenta.

Carbon monoxide (CO) is one of the metabolites formed via heme oxidation catalysed by the enzyme heme oxygenase (HO). Endogenous formation of CO, mediated by HO, has been noted in both placental and umbilical vessels. In blood vessels from different mammalian sources, it has been proposed that the vasodilator effect of CO is mediated via stimulation of soluble guanylyl cyclase (sGC) and consequent increased cGMP formation. The purpose of the present study was to determine the effect of exogenous CO on placental cotyledon perfusion pressure and to determine the role of sGC in the CO-induced decrease of perfusion pressure using the in vitro human placental perfusion preparation. A thromboxane A2 mimetic (U46619) was added to the foetal perfusion medium to constrict the placental blood vessels. Carbon monoxide was added to the foetal perfusion medium in increasing concentrations to determine its effect on placental perfusion pressure. Carbon monoxide produced a concentration-dependent decrease in placental perfusion pressure. The addition of ODQ, a sGC inhibitor, attenuated the CO-induced decrease in placental perfusion pressure, while addition of YC-1, an activator of sGC, augmented the CO-induced decrease in placental perfusion pressure. The data indicate that CO causes vasorelaxation of placental resistance blood vessels, in large part, via activation of sGC.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMedDate not supplied

Serum levels of type III procollagen peptide in Equidae before and after intestinal ischemia.

Serum levels of type III procollagen peptide (P-III-P) were measured by radioimmunoassay in clinically normal adult ponies (n = 15) and horses (n = 10). The mean serum levels of P-III-P from the ponies, 10.4 +/- 2.9 (SD) ng/mL, and the horses, 12.2 +/- 2.6 (SD) ng/mL, were not significantly different. Segments of jejunum were made ischemic to induce fibrous peritoneal adhesions in two ponies, and serum P-III-P levels were measured on days 4, 5, 7, 14, and 21. An exploratory celiotomy on day 21 revealed that the ischemic injury had induced fibrosis of the mesentery and bowel, but no adhesions had formed. The fibrotic mesentery contained type III collagen. The highest mean serum level of P-III-P, 23.0 +/- 3.5 (SD) ng/mL on day 7, was more than 4 SD above the mean from the normal ponies. There was a significant difference in the serum P-III-P levels in the ponies on days 0 (7.1 +/- 1.6 ng/mL) and 7 (23.0 +/- 3.5 ng/mL). Serum levels of P-III-P may be useful to study fibrosis associated with intestinal ischemia.

Animals↗
PubMedDate not supplied

Disposition of ethanol and its proximate metabolite, acetaldehyde, in the near-term pregnant ewe for short term maternal administration of moderate-dose ethanol.

The effect of short term maternal ethanol administration on the disposition of ethanol in the ovine maternal-fetal unit was determined. Eleven conscious instrumented near-term pregnant ewes (between 125 and 134 days of gestation; term, 147 days) received 1-hr iv infusion of 1 g of ethanol.kg of maternal body weight-1.day-1 for six days (N = 6 ewes) or an equivalent volume of saline for six days (N = 5 ewes). On the seventh day, the ethanol- and saline-pretreated animals were administered 1 g of ethanol.kg of maternal body weight-1. Ethanol and acetaldehyde concentrations were determined by headspace GLC in maternal blood, fetal blood, and amniotic fluid samples obtained at selected times during the 14-hr study. The data demonstrated that short term maternal administration of once-daily moderate dose ethanol did not produce major changes in the disposition of ethanol and its proximate metabolite, acetaldehyde, in the maternal, fetal, and amniotic fluid compartments during near-term ovine pregnancy.

Acetaldehyde↗