a-68828 and Acute-Kidney-Injury

Topics: Acute Kidney Injury; Amino Acid Sequence; Animals; Atrial Natriuretic Factor; Dose-Response Relationship, Drug; Glomerular Filtration Rate; Humans; Kidney; Molecular Sequence Data; Reperfusion Injury

Structure/activity studies on atrial natriuretic peptide ANP (1-28) have highlighted three portions of the native molecule as necessary for its biological responses. We have linked these three regions and excised the remaining segments to produce a family of small analogues (less than half the size of the parent) which demonstrate the full range of ANP's actions. Importantly, these compounds act at both major types of ANP receptor. Two critical modifications lead to more potent analogues; both involve expanding the cyclic portion of the molecule. Further optimization of one of these modified structures leads to A68828, a full ANP agonist which shows promise as a preventative agent against acute renal failure.

Topics: Acute Kidney Injury; Amino Acid Sequence; Animals; Atrial Natriuretic Factor; Binding, Competitive; Cyclic GMP; Diuresis; Dogs; Enzyme Activation; Guanylate Cyclase; Male; Molecular Sequence Data; Natriuresis; Peptide Fragments; Rabbits; Rats; Rats, Inbred Strains; Receptors, Atrial Natriuretic Factor; Receptors, Cell Surface; Structure-Activity Relationship

We have recently reported that administration of the ANF analog A68828 improves renal function in an acute model of postischemic acute renal failure. The current investigation examined the question whether a short-term infusion of A68828 can attenuate the long-term decrement in renal function following an ischemic event. Acute renal failure was induced in male Sprague-Dawley rats (200-250 g) by complete occlusion of both renal arteries for 30 min. During the initial 60 min following ischemia, vehicle (0.1% BSA in saline), A68828 (10 micrograms/kg/min); dopamine (10 micrograms/kg/min); A68828 (10 micrograms/kg/min) plus dopamine (10 micrograms/kg/min); or ANF[1-28] (0.5 microgram/kg/min) were infused intravenously. In vehicle-treated animals, a very large increase in plasma creatinine was observed, with peak levels at 2 days postischemia (5.5 +/- 1.2 mg/dL). A68828 alone, A68828 with dopamine, or ANF[1-28] infusion attenuated the rise in plasma creatinine levels by approximately 50% on each day of the study; dopamine alone was no different from vehicle-treated controls. Gross histological examination of kidneys on the fourth day postischemia revealed that significantly less damage occurred only in the group treated with A68828 alone. These results indicate that infusion of a reduced-size analog of ANF for a brief period in the postischemic kidney improves renal function and lessens tissue damage as evaluated several days after the ischemic event. Furthermore, dopamine infusion provides no discernable beneficial effect.

Topics: Acute Kidney Injury; Animals; Atrial Natriuretic Factor; Creatinine; Dopamine; Drug Therapy, Combination; Infusions, Intravenous; Ischemia; Kidney; Male; Organ Size; Rats; Rats, Inbred Strains

Experiments were conducted to determine the effects of the reduced-size atrial natriuretic factor (ANF) analog, A68828, on renal function in rats with cisplatin (CP)-induced acute renal failure. CP was given as a single intraperitoneal injection (7.5 mg/kg) 3 days before experiments. In separate groups of rats, the renal response to intravenous infusion of A68828 at 3, 10 or 30 micrograms/kg/min or ANF[1-28] at 0.03, 0.1 or 0.3 micrograms/kg/min for 2 hr was evaluated. Another group of CP-treated rats were infused with the vehicle (0.1% bovine serum albumin in 0.9% NaCl). CP treatment resulted in a marked decline in glomerular filtration rate (GFR), arterial pressure, heart rate and reabsorption of water and electrolytes compared to untreated control animals. Infusion of A68828 produced a dose-dependent improvement in the glomerular filtration rate. The highest dose of A68828 produced a nearly 3-fold increase in the glomerular filtration rate, whereas arterial pressure was decreased; heart rate was unchanged. Despite producing a significant diuresis and natriuresis, net tubular reabsorption of water and sodium was also increased. Similar dose-dependent effects were observed with the native peptide, ANF[1-28]. These data indicate that infusion of the reduced-sized analog of ANF, A68828, can significantly improve glomerular and tubular function in rats with acute renal failure induced by CP.

Topics: Acute Kidney Injury; Amino Acid Sequence; Animals; Atrial Natriuretic Factor; Cisplatin; Dose-Response Relationship, Drug; Glomerular Filtration Rate; Hemodynamics; Kidney; Male; Molecular Sequence Data; Natriuresis; Potassium; Rats; Rats, Inbred Strains; Renal Circulation

Short-term administration of atrial peptides has been reported to improve renal function in several animal models of acute renal failure. We designed experiments that determined the effect of a 13-amino acid analog of atrial natriuretic factor (ANF), A68828, on renal function in the postischemic model of acute renal failure. Experiments were conducted using euvolemic, male Sprague-Dawley rats (200-250 g) under Inactin anesthesia. Acute renal failure was induced by complete occlusion of both renal arteries for 30 min. After release of the clamp, vehicle (0.1% bovine serum albumin in saline), A68828 (3, 10 or 30 micrograms/kg/min), dopamine (10 micrograms/kg/min), A68828 (10 micrograms/kg/min) plus dopamine (10 micrograms/kg/min) or ANF (1-28) (0.5 micrograms/kg/min) were infused i.v. for a 2-h period. A68828 at 10 micrograms/kg/min produced a significant increase in glomerular filtration rate (GFR) compared with vehicle controls (0.39 +/- 0.08 vs. 0.19 +/- 0.04 ml/min/100 g; P less than .05) despite a lower arterial pressure (87 +/- 5 vs. 101 +/- 5 mm Hg; P less than .05). A subpressor dose of dopamine had no effect on GFR during the postischemic period (0.25 +/- 0.11 ml/min/100 g). Dopamine in combination with A68828 prevented the decrease in arterial pressure seen with A68828 alone but did not potentiate the beneficial effects on GFR (0.28 +/- 0.05 ml/min/100 g). ANF (1-28) at 0.5 micrograms/kg/min increased GFR to levels nearly identical to those induced by A68828 (0.40 +/- 0.04 ml/min/100 g). These results indicate that infusion of a reduced-size analog of ANF improves renal function in the immediate postischemic period. Furthermore, prevention of the hypotensive effects of the analog with dopamine provides no additional beneficial effect.

Topics: Acute Kidney Injury; Amino Acid Sequence; Animals; Atrial Natriuretic Factor; Blood Pressure; Dopamine; Drug Therapy, Combination; Glomerular Filtration Rate; Heart Rate; Ischemia; Kidney; Kidney Tubules; Male; Molecular Sequence Data; Rats; Rats, Inbred Strains; Sodium; Time Factors