Role of K+ channels in L-6 myoblast migration.

Migration of myoblasts is an important component of the reparative response to muscle injury, and furthermore may be a key determinant of the success of myoblast transplantation for the treatment of genetic muscle diseases. The present study examined the hypothesis that K+ channels modulate myoblast migration. The migration of cultured L-6 myoblasts was assessed in vitro on confluent cultures with the razor wound method, in the absence and presence of the following agents: 3,4-diaminopyridine and tetraethylammonium (which block several types of K+ channels), apamin and charybdotoxin (which block Ca++-activated K+ channels), glibenclamide (which blocks ATP-sensitive K+ channels), and alpha-, beta-, gamma-, and delta-dendrotoxin (which block voltage-gated K+ channels).

Inhibition of endothelial cell migration by cigarette smoke condensate.

Cigarette smoking is among the leading risk factors in the etiology of atherosclerotic vascular disease. The mechanism, however, that links cigarette smoking to an increased incidence of atherosclerosis is poorly understood. Endothelial cell (EC) integrity is critical in preventing vascular lesion formation, and after a loss of EC integrity reendothelialization must be rapid and complete.

The migratory response to platelet-derived growth factor of smooth muscle cells isolated from synthetic vascular grafts in a canine model.

Objective: Previous studies on smooth muscle cells (SMCs) harvested from implanted synthetic grafts demonstrate increased production of platelet-derived growth factor (PDGF) but decreased proliferative response compared with aortic SMCs. The purpose of this study was to determine the migratory response of graft versus aortic SMCs.

Methods: Thoracoabdominal grafts were implanted in beagles.

Attenuation of rat diaphragm low-frequency fatigue by vanadate in vitro.

Sodium vanadate inhibits protein tyrosine phosphatases, including in skeletal muscle. Vanadate increases contractile force of airway, vascular and gastrointestinal smooth muscle. The present study tested the hypothesis that vanadate augments skeletal muscle contractility.

Aortic smooth muscle contains guanylate-cyclase-coupled 130-kDa atrial natriuretic factor receptor as predominant receptor form. Spontaneous switching to 60-kDa C-receptor upon cell culturing.

Photoaffinity labeling of atrial natriuretic factor (ANF) receptor in the plasma membranes from bovine aortic smooth muscle tissue using N alpha 5-(4-azidobenzoyl)-ANF-(5-28)- peptide labeled with 125I yielded a 130-kDa band. However, when smooth muscle cells from the same bovine aorta were placed in culture, the 130-kDa receptor quickly disappeared and a 60-kDa band began to appear at high density. After three passages, essentially no 130-kDa band was found and only the 60-kDa band was strongly labeled.

HS-142-1, a Novel Non-peptide Antagonist for Atrial Natriuretic Peptide Receptor, Selectively Inhibits Particulate Guanylyl Cyclase and Lowers Cyclic GMP in LLC-PK1 Cells.

HS-142-1, a novel atrial natriuretic peptide (ANP) antagonist isolated from the culture broth of Aureobasidium sp., selectively inhibits ANP-induced cyclic GMP accumulation in porcine kidney epithelial LLC-PK1 cells. At concentrations from 0.

Reconstitution of solubilized V1 vasopressin receptors of human platelets.

We describe the reconstitution of solubilized human platelet arginine vasopressin (AVP) receptors into phospholipid vesicles. Purified platelet plasma membranes enriched in AVP receptors [binding equilibrium dissociation constant (Kd) = 1.87 +/- 0.

Solubilization and identification of human placental endothelin receptor.

Endothelin-1 (ET-1) receptor was identified on the membranes from human placenta and 66% of original binding activity in the membranes was solubilized with 0.75% (w/v) CHAPS. Binding studies of the solubilized membranes using 125I-ET-1 indicated the presence of a single class of high-affinity binding sites with an apparent Kd of 760 pM and a Bmax of 1.

Identification of two types of specific endothelin receptors in rat mesangial cell.

Two types of receptors specific for endothelin were identified using cross-linking technique in cultured rat mesangial cells. The molecular weights of these receptors were approximately 58,000 and 34,000 by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate. The binding of radioiodinated-endothelin to its receptors was inhibited by excess of unlabeled endothelin, but not by nifedipine, nicardipine, verapamil, diltiazem, angiotensin II or [Arg8]-vasopressin.

High and low affinity binding sites for endothelin on cultured rat glomerular mesangial cells.

Endothelin contracts glomerular mesangial cells, thereby influencing glomerular size and filtration rate. Here, we demonstrate the presence of two ET-specific binding sites on cultured rat mesangial cells with Kds of 0.76 and 44.

Release of atrial natriuretic factor from heart-lung preparations of inbred Dahl rats.

Isolated heart-lung preparations from hypertensive inbred Dahl salt-hypertension sensitive (S) and normotensive inbred Dahl salt-hypertension resistant (R) rats were perfused using 15% washed rat red blood cells in Krebs-Ringer bicarbonate buffer. Atrial pressures were increased by increasing venous return (preload) or by increasing the arterial resistance (afterload). Increases in preload at a constant afterload produced increases in the right and left atrial pressures equivalent between S and R strains.

Two distinct forms of receptors for atrial natriuretic factor in bovine adrenocortical cells. Purification, ligand binding, and peptide mapping.

The atrial natriuretic factor (ANF) receptor of bovine adrenal cortex was solubilized with Triton X-100 and purified by sequential chromatography on ANF-(99-126)-agarose, GTP-agarose, and wheat germ agglutinin-Sepharose. Two subtypes of ANF receptors were isolated, both of which showed specific ANF binding, whereas one of the ANF receptor subtypes also possessed significant cyclase activity. Both of the receptors showed high capacities (Bmax = 5.

Partial characterization of atrial natriuretic factor in the hearts of Dahl salt-sensitive and salt-resistant rats.

Atria of adult Dahl salt-sensitive rats contain more atrial natriuretic factor (ANF) than those of Dahl salt-resistant rats, as measured by RIA. This strain difference was not seen at 15 days of age, but was observed at and after 30 days of age. Neither a sodium-deficient diet nor an 8% NaCl diet started as early as 2 weeks of age altered this strain difference, although high dietary NaCl was associated with reduced atrial ANF concentration.

Purification and characterization of two types of atrial natriuretic factor receptors from bovine adrenal cortex: guanylate cyclase-linked and cyclase-free receptors.

Atrial natriuretic factor (ANF) receptors with and without guanylate cyclase activity were simultaneously purified to apparent homogeneity from bovine adrenal zona glomerulosa cell membrane fractions. The particulate guanylate cyclase which co-purified with the ANF receptor showed one of the highest specific activity reported. The receptors with or without the guanylate cyclase activity showed high affinities to ANF (99-126).

Atrial natriuretic factor in inbred Dahl salt-sensitive and salt-resistant rats.

The atria of adult Dahl salt-sensitive (S) rats contain more atrial natriuretic factor (ANF) than the atria of adult Dahl salt-resistant (R) rats by both radio-immunoassay and bioassay. This strain difference is not present between 1 and 15 days of age but is present at 30 days of age and persists throughout adulthood. The precursors of ANF immunoprecipitated from in vitro translations of atrial messenger RNA (mRNA) had the same molecular weight in S and R strains.

Characterization of vasopressin receptors of rat urinary bladder and spleen.

By use of tritiated arginine-8-vasopressin (AVP), vasopressin specific binding sites were detected on Sprague-Dawley rat urinary bladder and spleen. In both tissues, one class of high-affinity binding sites was characterized with an equilibrium dissociation constant of 1.61 +/- 0.

Elevated atrial natriuretic polypeptide in plasma of hypertensive Dahl salt-sensitive rats.

The relationship between circulating atrial natriuretic polypeptide (ANP) and blood pressure was studied in inbred Dahl salt-sensitive (S) and inbred Dahl salt-resistant (R) rats. Two month old S and R rats raised on normal rat chow had only small differences in blood pressure and no difference in plasma ANP levels. In contrast, when 6-month-old rats also raised on normal chow were studied, S had markedly elevated blood pressure and a 4 fold increase in plasma ANP compared to R.

[Regulation of V1-vasopressinergic receptors in the rat].

Using tritiated vasopressin, specific binding sites for vasopressin were identified on splenic membranes of Sprague-Dawley rats. One class of high affinity receptors was characterized with an equilibrium dissociation constant of 1.91 +/- 0.

Atrial natriuretic factor in Dahl rats. Atrial content and renal and aortic responses.

Inbred Dahl salt-sensitive rats had a higher content of atrial natriuretic factor by bioassay in their atria than did inbred Dahl salt-resistant rats. This finding was true both in young 1- to 2-month-old rats, when blood pressure differences between strains were small, and in 7-month-old rats, when blood pressure differences were marked. Atria from salt-sensitive rats had more atrial natriuretic factor than did atria from salt-resistant rats when the rats were fed either low (0.

Spontaneous nephrotic syndrome in a genetic rat model.

Advances in our understanding of the mechanisms of proteinuria in humans have depended on a variety of animal models. Most of these have been partially satisfactory because they require pretreatment of the animal with chemicals or toxins or they depend on an aging-related glomerular protein leakiness. The strain in this study was obtained by Koletsky after selective inbreeding of the offspring from a hypertensive Kyoto-Wistar and a normotensive Sprague-Dawley rat.

Inhibition of aldosterone production by atrial natriuretic factor.

Extracts of rat atrial muscle lowered basal aldosterone release from rat adrenal glomerulosa cell suspensions, and partially inhibited the stimulation of aldosterone release by adrenocorticotropic hormone (ACTH) and angiotensin II. Atriopeptin I, an atrial peptide with natriuretic, diuretic and smooth muscle relaxant activities, significantly decreased basal aldosterone release at 1 pM concentrations. Also, atriopeptin I decreased the sensitivity of the glomerulosa cells to adrenocorticotropin and angiotensin II.

Inhibition of aldosterone production by an atrial extract.

Crude extracts of rat atria reduced the basal amount of aldosterone released from rat zona glomerulosa cells and partially inhibited aldosterone stimulation by adrenocorticotropic hormone and angiotensin II. The destruction of this activity by trypsin suggests that the active factor is a peptide, possibly atrial natriuretic factor. These data suggest that atrial natriuretic factor affects sodium excretion by the kidneys both directly and through the inhibition of aldosterone production.

Atherosclerosis following balloon catheter injury to the carotid artery and the aorta of hypertensive rats with normolipidemia or hyperlipidemia.

The carotid artery and abdominal aorta of hypertensive normocholesterolemic rats responded in similar manner to balloon denuding of the endothelium. One denuding resulted in an intimal fibrous plaque, while multiple such injuries increased the lipid content of the plaque and so yielded fatty-fibrous plaques, which perhaps represent an intermediate stage of atherosclerosis. In no instance did a single or multiple denuding lead to advanced atherosclerosis.