Transition from fetal to extrauterine circulation.

In utero, there is increased pulmonary vascular resistance favoring minimal pulmonary blood flow and right-to-left shunting of blood through the ductus arteriosus and foramen ovale. Delivery initiates a series of complex biochemical and structural changes whereby the neonate assumes those processes critical to survival. This article reviews fetal circulation, the characteristics of the fetal cardiopulmonary system, and the transition from fetal to neonatal circulation. It also discusses the consequences of disrupted transition to extrauterine life and the relationship between fetal cardiopulmonary anatomy and congenital heart disease.

Pharmacologic treatment of neonatal sepsis: antimicrobial agents and immunotherapy.

Antimicrobial agents and immunotherapies in the management of neonatal sepsis are discussed. The rationale for the selection of the most commonly used antibacterial drugs, their mechanisms of actions, and indications for use are described. Immunotherapies, both those in clinical use and those under investigation, are discussed. Antibacterial drugs remain the standard of care, but immunotherapy offers the potential for improving outcomes for neonates, especially those who are premature.

The effects of insulin on vasoconstrictor responses in pithed rats.

Pressor responses to spinal sympathetic outflow and selected vasoactive agents were examined in control and diabetic Wistar-Kyoto pithed rats. Diabetes was induced by intravenous injection of alloxan (50 mg/kg). One week after the diabetogen, some of the rats were treated with one daily subcutaneous injection of Lente insulin (2 U/100 Gm) for five weeks. All rats were pithed at six weeks after alloxan. Vasoconstrictor responses to spinal sympathetic outflow, serotonin, norepinephrine, tyramine, and angiotensin were reduced in diabetic rats as compared to their age-matched controls. Administration of insulin caused only partial normalization of these responses. Nondiabetic rats given insulin exhibited vascular responsiveness similar to the treated diabetic group of animals. Blood pressures and heart rates were also found to be similar between the insulin-treated groups and significantly less than control. The finding that insulin does not produce complete normalization of vasoconstrictor responsiveness in diabetic rats may be relevant to the reduced blood pressure observed following insulin treatment.

Cardiovascular effects of alloxan diabetes in normotensive and spontaneously hypertensive rats.

The diabetogenic effects of alloxan (50 mg/kg i.v.) were recorded for 6 weeks in normotensive (WKY) and spontaneously hypertensive (SHR) rats. While systolic blood pressure increased in diabetic WKY, SHR exhibited a reduction in systolic blood pressure over the 6-week period. Heart rate of treated SHR, but not WKY, was reduced significantly during the course of diabetes. 6 weeks postalloxan, the pressor responses to spinal cord stimulation and various vasoactive agents were significantly reduced in both diabetic groups as compared to their age-matched controls. However, in vitro preparations taken from diabetic and control WKY rats showed similar responsiveness to vasoactive agents. The data suggest that circulatory factors contribute to the decreased in vivo responsiveness.