Arterial responses in vitro and plasma digoxin immunoreactivity after losartan and enalapril treatments in experimental hypertension.

Treatment with the angiotensin-converting enzyme inhibitor, quinapril, has been shown to normalize increased dihydropyridine sensitivity and impaired potassium relaxation, characteristic features of arterial smooth muscle in spontaneously hypertensive rats, and also reduce the concentration of plasma digoxin-like immunoreactivity in these animals. However, whether angiotensin II receptor blocker therapy can beneficially influence these variables is not known. Therefore, we compared the effects of 10-week losartan and enalapril treatments (15 and 4 mg/kg/day, respectively) on functional responses of mesenteric arterial rings in spontaneously hypertensive rats and Wistar-Kyoto rats.

Only a small portion of the cytoplasmic progesterone receptor is associated with Hsp90 in vivo.

In cell extracts all of the nonliganded steroid receptor molecules are found as an oligomeric complex with Hsp90 and other proteins. In previous studies we have shown that Wild-type Hsp90 and progesterone receptor (PR) are located in different cell compartments (Tuohimaa et al. [1993] Proc.

Reappraisal of the role of heat shock proteins as regulators of steroid receptor activity.

Almost 30 years have passed since the original demonstration that steroid receptors, comprising a subfamily of the nuclear receptor (NR) superfamily, exist as large (6-8S) non-DNA-binding complexes in hypotonic extracts (cytosol) of target cells; later such complexes were shown to correspond to a heterooligomer composed of receptor, heat shock (Hsp), and other proteins. Subsequently, an impressive number of studies have dealt with the composition of the "nonactive" complex, its dissociation and/or reassembly in vitro, possible functions of the non-receptor components, and their subcellular compartmentalization. While there is little dispute about the chaperoning role of some Hsps in such a complex, there is still no final proof of an association in vivo of NRs and Hsps in the nuclei of target cells, which is requisite for a direct regulatory involvement of Hsps in NR function.

Effect of celiprolol therapy on arterial dilatation in experimental hypertension.

1. It has recently been suggested that therapy with beta-adrenoceptor blockers reduces peripheral arterial resistance via enhanced vascular dilatation. Therefore, we studied the effects of celiprolol, which is a specific beta 1-antagonist that has a weak beta 2-agonist action, on arterial tone in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats.

Hormone-dependent changes in A and B forms of progesterone receptor.

The influence of different estrogen and/or progesterone treatments on concentrations of A and B forms of progesterone receptor (PR-A and PR-B) in the different cell types of chick oviduct was studied. A semiquantitative immunohistochemical assay for cellular PR concentrations was developed using a computer-assisted image analysis system. The staining intensity of nuclear PR in the basal layer of epithelial cells, glandular, smooth muscle and mesothelial cells was analysed separately using two monoclonal antibodies, PR6 and PR22.

Angiotensin-converting enzyme inhibition attenuates arterial constrictor responses in experimental hypertension.

Angiotensin-converting enzyme inhibition has been shown to attenuate arterial contractions, but the underlying mechanisms have not been clarified in detail. Therefore, we investigated the effects of 10-week-long quinapril therapy (10 mg kg-1 day-1) on responses of mesenteric arterial rings in vitro in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats. The hypertrophy of cardiac muscle and mesenteric arterial smooth muscle was effectively reduced in SHR by quinapril treatment.

Mechanisms of action of sex steroid hormones: basic concepts and clinical correlations.

The review deals with the clinically important aspects of the basic mechanisms of sex steroid hormones. Steroids can act through two basic mechanisms: genomic and non-genomic. The classical genomic action is mediated by specific intracellular receptors, whereas the primary target for the non-genomic one is the cell membrane.

Progesterone receptor does not form oligomeric (8S), non-DNA-binding complex in intact cell nuclei.

We raised a polyclonal antibody, alpha D, against a synthetic peptide (amino acids 522-535) of chicken progesterone receptor (PR). The sequence is located between the DNA-binding domain and the hormone-binding domain in the region within the sequences required for stability of the oligomeric form of PR. In the immunoblot, alpha D reacted with both A and B forms of PR.

Progesterone receptor and hsp90 are not complexed in intact nuclei.

In hypotonic cell extract (cytosol), unliganded progesterone receptor (PR) is known to form an oligomeric complex with heat shock protein 90 (hsp90), and this complex does not bind to DNA. Since ligand binding has been shown to render the complex less stable in vitro, it has been proposed that ligand binding regulates DNA binding and receptor activity in vivo by altering the stability of the oligomeric complex. However, there is no direct evidence as to whether this oligomeric complex is present in vivo.

Nuclear progesterone receptor is mainly heat shock protein 90-free in vivo.

Heat shock protein 90 (hsp90) is associated with many steroid receptors in tissue homogenates. It is widely accepted that hsp90 regulates the binding of the receptor to the corresponding gene regulatory element. However there is no unequivocal evidence that steroid receptor-hsp90 complexes are present in the intact cells.

Quinapril treatment and arterial smooth muscle responses in spontaneously hypertensive rats.

1 The effects of long-term angiotensin-converting enzyme inhibition with quinapril on arterial function were studied in spontaneously hypertensive rats, Wistar-Kyoto rats serving as normotensive controls. 2 Adult hypertensive animals were treated with quinapril (10 mg kg-1 day-1) for 15 weeks, which reduced their blood pressure and the concentrations of atrial natriuretic peptide in plasma and ventricular tissue to a level comparable with that in normotensive rats. 3 Responses of mesenteric arterial rings in vitro were examined at the end of the study.

Contractions induced by potassium-free solution and potassium relaxation in vascular smooth muscle of hypertensive and normotensive rats.

1. Vascular contractions induced by K(+)-free solution and relaxation responses following the return of K+ to the organ bath were studied in mesenteric arterial rings from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) with particular focus on the role of vascular adrenergic nerve-endings and endothelium. 2.

Subcellular location of unoccupied and occupied glucocorticoid receptor by a new immunohistochemical technique.

Recent immunohistochemical studies suggest that the unoccupied glucocorticoid receptor (GR) is cytoplasmic and that the ligand causes its translocation into the target cell nucleus. The subcellular location of GR is especially interesting in that other members of the steroid receptor superfamily appear to be nuclear. The intracellular distribution of GR was studied immunohistochemically using a new freeze-drying and vapor fixation method which eliminates the protein diffusion and redistribution possibly caused by liquid fixation techniques.

Subcellular location of androgen receptor in rat prostate, seminal vesicle and human osteosarcoma MG-63 cells.

Location of the androgen receptor (AR) before and after dihydrotestosterone (DHT) administration was studied in 6 castrated and 2 normal male rats, as well as in MG-63 human osteosarcoma cell culture. Two days after castration, rats were injected with DHT and sacrificed 0, 6 and 24 h later. Cryosections of ventral prostate and seminal vesicle were stained with a polyclonal anti-AR antibody.

Different immunoelectron microscopic locations of progesterone receptor and HSP90 in chick oviduct epithelial cells.

The intracellular locations of the components of the heterooligomeric progesterone receptor (PR), heat-shock protein (hsp90), and the ligand-binding component were studied by immunoelectron microscopy in the chick oviduct, using immunogold double labeling and peroxidase techniques with monoclonal antibodies (MAb) against hsp90 (7D alpha and 4F3) and against PR (PR6 and PR13). PR was located in the nuclei of epithelial cells independently of the presence or absence of ligand. Cells with apically located nuclei were often PR negative.

New freeze-dry and vapor fixation method for immunohistochemistry of soluble proteins: subcellular location of the progesterone receptor.

We describe a new application of freeze-drying and vapor fixation for immunohistochemical location of soluble proteins. The method avoids the liquid phase, which eliminates the possible diffusion of soluble proteins. Two vapor fixatives, paraformaldehyde and p-benzoquinone, were tested and p-benzoquinone was found to preserve antigenicity of progesterone receptor (PR) and ovalbumin better than paraformaldehyde.

Development of progestin-specific response in the chicken oviduct.

Avidin is a host acute defense protein induced by progestins and by inflammation caused by injurious factors such as microbes, viruses, toxic factors or tissue trauma. In the reproductive tract of egg-laying vertebrates avidin has evolved into a progestin-dependent secretory protein involved in anti-microbial action through its biotin avidity. For "progestin-dependent avidin" production, cellular differentiation by estrogen is necessary.

Progesterone receptor concentration differences in the chick oviduct cells and apparent down-regulation by ligand. A semiquantitative immunohistochemical study.

A semiquantitative immunohistochemical technique was developed for identification of chick progesterone receptor (PR). The mouse monoclonal antibody PR6 was used. The nuclear PR concentration was analyzed with Leitz Orthoplan MPV-3 light microscope.

Progesterone receptor is constitutively expressed in chicken intestinal mesothelium and smooth muscle.

We have previously shown that progesterone receptor (PR) is expressed in the mesothelium of the chick oviduct and ovary and in the smooth muscle cells of the oviduct and the bursa of Fabricius. Here, we investigated the presence of PR in different parts of the peritoneum and abdominal organs using an immunohistochemical staining based on monoclonal antibodies against chicken PR. In 4-week-old sexually immature chicks, PR expression was located in the mesothelial cells of different parts of the peritoneum, in a thin layer of muscle cells of the ileum and throughout the muscle tissue of the colon and cloaca.