The urinary excretion of kallikrein, an enzyme which cleaves a vasodilator kinin from kininogen substrate, was examined in three types of hypertensive rats. Enzyme activity was measured by both esterase activity (isotopic assay) and bioassay with purified rat urinary kallikrein as a standard. Excretion of kallikrein was found to increase with age in spontaneously hypertensive rats, but levels w...

The mechanisms that mediate renal "escape" from the sodium-retaining effects of mineralocorticoids are incompletely understood. This study was undertaken to determine whether atrial natriuretic peptide (ANP) may play a role in the escape phenomenon. Immunoreactive ANP in rat plasma increased 2.5-fold above baseline values at 12 and 24 h after a single depot injection of desoxycorticosterone ace...

This study was designed to examine whether prostaglandin E2 can directly affect sodium transport across isolated perfused rabbit renal collecting tubules. Changes in transepithelial potential and isotopic sodium fluxes in response to peritubular prostaglandin E2 were measured. In addition, changes in transepithelial potential of the outer medullary collecting tubule in response to prostaglandin...

In a study of a group of hospitalized patients in whom there was no reason to suspect a disturbed acid-base balance, it was found that a few patients had low blood pH values. The only factor in common to these patients with the low pH values was that all had essential hypertension. It has been demonstrated in human subjects that experimental hypertension can be produced with desoxycorticosteron...

Water-free Na+ storage may buffer extracellular volume and mean arterial pressure (MAP) in spite of Na+ retention. We studied the relationship among internal Na+, K+, water balance, and MAP in Sprague-Dawley rats, with or without deoxycorticosterone-acetate (DOCA) salt, with or without ovariectomy (OVX). The rats were fed a low-salt (0.1% NaCl) or high-salt (8% NaCl) diet for 5 weeks. DOCA salt...

I N A previous study (I) it was found that the response of rat muscle to single stimuli showed a greater developed tension and a longer contraction time in adrenalectomized animals than in normal controls. The increased contraction time and the prolonged action potentials observed after adrenalectomy led to the suggestion that repetition might account for a part of the increased tension. In the...

BACKGROUND Crocus sativus L. (saffron), which belongs to the Iridaceae family, is widely cultivated in Iran. Cardiovascular effects of saffron has been established in some studies but the effects of chronic administration of saffron (C. sativus) stigma aqueous extract on blood pressure has not been investigated. OBJECTIVES In this study the effects of saffron (C. sativus) stigma aqueous extra...

The present study was aimed at investigating the regulation of atrial natriuretic peptide (ANP) system in association with either enhanced or attenuated activity of the renin-angiotensin system (RAS). The cardiac tissue mRNA and peptide levels of ANP were measured in rats with two-kidney, one clip (2K1C) or deoxycorticosterone acetate (DOCA)-salt hypertension. Plasma renin concentration was inc...

OBJECTIVES Auraptene, a monoterpene coumarin from Citrus species, exhibits cardioprotective effects. In this study, the effects of auraptene administration were investigated on blood pressure of normotensive and desoxycorticosterone acetate (DOCA) salt induced hypertensive rats. MATERIALS AND METHODS Five weeks administration of auraptene (2, 4, 8 and 16 mg/kg/day) and nifedipine (0.25, 0.5, ...

Although alpine meadows of Tibet are expected to be strongly affected by climatic warming, it remains unclear how soil organic C (SOC), total N (TN), ammonium N (NH4 (+)-N) , nitrate N (NO3 (+)-N), and dissolved organic C (DOC) and N (DON) respond to warming. This study aims to investigate the responses of these C and N pools to short-term experimental warming in an alpine meadow of Tibet. A wa...