P2 Purinoceptor Saturation by Adenosine Triphosphate Impairs Renal Autoregulation in Dogs

P2 purinoceptor saturation by adenosine triphosphate impairs renal autoregulation in dogs.

Recent studies have suggested a role for P2 purinoceptors on vascular smooth muscle cells in the mechanism of renal autoregulation. Experiments were performed in anesthetized dogs (n = 9) to examine renal blood flow (RBF) autoregulatory efficiency before and after saturation of P2 purinoceptors with acute intra-arterial administration of ATP (1 mg/kg per min). Dogs were pretreated with the nitr...

Direct assessment of renal microvascular responses to P2-purinoceptor agonists.

Studies were performed to determine the responsiveness of rat juxtamedullary afferent arterioles to receptor-selective P2-purinoceptor agonists. Experiments were performed in vitro using the blood perfused juxtamedullary nephron technique, combined with videomicroscopy. Renal perfusion pressure was set at 110 mmHg and held constant. Basal afferent arteriolar diameter averaged 22.0 ± 0.6 μm ( n ...

Adenosine 59-Triphosphate: a P2-Purinergic Agonist in the Myocardium

Adenosine 5'-triphosphate: a P2-purinergic agonist in the myocardium.

ATP, besides an intracellular energy source, is an agonist when applied to a variety of different cells including cardiomyocytes. Sources of ATP in the extracellular milieu are multiple. Extracellular ATP is rapidly degraded by ectonucleotidases. Today ionotropic P2X(1--7) receptors and metabotropic P2Y(1,2,4,6,11) receptors have been cloned and their mRNA found in cardiomyocytes. On a single c...

Hyperglycemia impairs retinal oxygen autoregulation in normal and diabetic dogs.

Preretinal oxygen tensions were measured continuously using microelectrodes in four normal dogs and four dogs made diabetic with alloxan. The latter were kept under poor control for 8 months. Glucose administered intravenously in 30 to 90 sec to all the dogs when they were normoglycemic caused an immediate increase in preretinal oxygen tension lasting approximately 10 min. When the dogs were gi...