Effectiveness of dietary essential fatty acid deficiency in development of a model of endogenous renal prostaglandin deficiency

Acute prostaglandin reduction with indomethacin and chronic prostaglandin reduction with an essential fatty acid deficient diet both decrease plasma flow to the renal papilla in the rat

Renal distribution of prostaglandin synthetase is mainly medullary, whereas the major degrading enzyme, prostaglandin dehydrogenase is primarily cortical. This suggests that prostaglandins (PG) released from the renal medulla could affect the medullary blood vessels. In two different experiments we studied the role of PG in the regulation of renal papillary plasma flow in the rat. First study: PG synthesis were stimulated in 34 adult Sprague-Dawley rats by bleeding from the femoral artery 1% of the body weight over a period of 10 minutes. Following this, indomethacin (a PG inhibitor, 10 mg/kg i.v.) was given slowly and then renal papillary plasma flow was measured 25 minutes after the end of infusion. In 17 indomethacin rats the renal papillary plasma flow averaged 18.8 ml/100 g/minute, whereas it averaged 23.0 in 17 non-indomethacin rats given diluent, an 18% reduction (p less than .025). Second study: Male Sprague-Dawley rats were made prostaglandin deficient by fasting rats for one week, followed by 10% dextrose fluid for one week and subsequent institution of an essential fatty acid (EFA) deficient diet for two weeks. With urinary PG excretion in prostaglandin deficient rats 28 ng/24 hours compared to 149 ng in control rats, they could be considered as prostaglandin deficient. When renal papillary plasma flow was measured, the 16 prostaglandin deficient rats had a 16% lower papillary plasma flow than 16 control rats, 21.6 vs 25.6 (p less than .005). These results clearly demonstrate that PG inhibition in rats decreases plasma flow to the papilla, strongly suggesting that PG are vasodilators for the vessels supplying the renal papilla.

Decreased lipid intake reduces morbidity in sick premature neonates

For an investigation of the clinical sequelae of parenteral lipid infusions during the first week of life, 42 neonates (less than 1750 gm birth weight) were randomly assigned to receive parenteral alimentation with (IL) (Vitrum) or without a parenteral lipid infusion (NL) for 5 days. Follow-up clinical status was monitored and compared, and plasma prostaglandin levels were analyzed. Chronic lung disease was increased in duration and tended to be more severe after lipid administration. The number of days of mechanical ventilation (37 +/- 35 vs 21 +/- 18) and supplemental oxygen therapy (51 +/- 39 vs 28 +/- 23) was significantly increased in the IL group. Five IL infants developed stage 3 bronchopulmonary dysplasia, in comparison with none of the NL infants. Seven IL infants were discharged on a regimen of supplemental oxygen therapy versus none of the NL infants. Thromboxane B2 levels were significantly increased in the babies receiving Vitrum. We conclude that early administration of Vitrum in the premature neonate is associated with increased respiratory difficulty in the ensuing weeks of life.