Increases in myocardial cyclic GMP attenuate contractile delay in myocardial stunning

Nesiritide during extracorporeal membrane oxygenation

Nesiritide is a recombinant formulation of B-type natriuretic peptide (BNP). Preliminary experience in the adult population has shown nesiritide to be an effective agent in the treatment of decompensated congestive heart failure (CHF) in adults. Given its physiological effects, it may be an effective agent in other clinical scenarios. We report the use of nesiritide in two infants during extracorporeal membrane oxygenation (ECMO). In one patient, nesiritide in doses up to 0.09 microg.kg(-1).min(-1) were used to control mean arterial pressure while in the other patient, doses of 0.01-0.03 microg.kg(-1).min(-1) were used to augment urine output. The potential applications of nesiritide and dosing regimens for this agent in the ECMO population are discussed.

Negative metabolic and coronary flow effects of decreases in cAMP and increases in cGMP in control and renal hypertensive rabbit hearts

The interaction during stimulation of cGMP and inhibition of cAMP was investigated in control and renal hypertensive hearts. Control and hypertensive [1 kidney, 1 clip (1K1C)] rabbits were used. The anesthetized open-chest groups were vehicle, 8-bromo-cGMP (8-Br-cGMP; 10(-3)M), propranolol (Prop; 2 mg/kg), and Prop + 8-Br-cGMP. O(2) consumption levels (Vo(2)) in the subepicardium (Epi) and subendocardium (Endo) were determined from coronary flow (microspheres) and O(2) extraction (microspectrophotometry). Wall thickening and cAMP levels were also determined. In control, no significant change in Vo(2) was seen for the 8-Br-cGMP group, but Vo(2) was decreased from Epi (9.7 +/- 1.5 ml O(2) x min(-1) x 100 g(-1)) and Endo (10.5 +/- 0.4 ml O(2) x min(-1) x 100 g(-1)) to 6.8 +/- 0.6/7.8 +/- 0.5 ml O(2) x min(-1) x 100 g(-1) in the control Prop group. Control Prop + 8-Br-cGMP did not cause a further fall in Vo(2) but lowered Endo flow. In 1K1C, Vo(2) decreased from Epi/Endo (10.8 +/- 1.3/11 +/- 1.0 ml O(2).min(-1).100 g(-1)) to 7.8 +/- 1.1/8.7 +/- 0.5 ml O(2) x min(-1) x 100 g(-1) in the 1K1C 8-Br-cGMP group and to 7 +/- 0.5/8.1 +/- 0.5 ml O(2) x min(-1) x 100 g(-1) in the 1K1C Prop group. 1K1C Prop + 8-Br-cGMP did not cause a further fall in Vo(2) but lowered blood flow. No significant changes in cAMP levels were present with 8-Br-cGMP in control or 1K1C rabbits, but significant decreases were seen with Prop in both control and 1K1C rabbits. No further change was seen in Prop + 8-Br-cGMP for either control or 1K1C. Thus the negative metabolic effect of stimulating cGMP was seen only in the hypertensive rabbit heart. The negative metabolic effect of inhibiting cAMP was seen in both the control and the hypertensive rabbit heart. However, the negative metabolic effects of cGMP and cAMP were nonadditive.