Radiological lung sequelae, functional status and symptoms in older patients 3 and 6 months after hospitalization for COVID-19 pneumonia

The aim of our study was to assess the lung sequelae and clinical consequences 3 and 6 months after hospitalization for COVID-19 pneumonia in older patients. An observational study was conducted on 55 patients aged 65 years and older. Activities of daily living (ADL) and clinical frailty scale (CFS) were assessed at baseline and after 3 months. Both quantitative assessment at chest high-resolution computed tomography (CT) and semi-quantitative severity score (CTSS) were performed at baseline and after 3 and 6 months. Mean age: 82.3 ± 7.1 years. Male prevalence: 56.4%. After 6 months, ground-glass opacities (GGO) were still detectable in 22% of subjects, while consolidations were no longer appreciable. During follow-up, CTSS reached an overall median score of zero after 6 months. Fibrotic-like changes were found in 40% of subjects with an overall median score of 0 (0-5) points, being more prevalent in males. Patients reporting worsening ADL and CFS were 10.9% and 45.5%, respectively. They were associated with the burden of comorbidities, especially history of heart failure and chronic obstructive pulmonary disease at baseline. Amnesic disorders, exertional dyspnea, and fatigue were the most relevant symptoms reported. No association emerged between persistent or new-onset symptoms and evidence of fibrotic-like changes. The typical chest CT abnormalities of the COVID-19 pneumonia acute phase resolved in most of our older patients. Mild fibrotic-like changes persisted in less than half of the patients, especially males, without significantly affecting the functional status and frailty condition, which instead were more likely associated with pre-existing comorbidities.

Role of Cardiac Natriuretic Peptides in Heart Structure and Function

Cardiac natriuretic peptides (NPs), atrial NP (ANP) and B-type NP (BNP) are true hormones produced and released by cardiomyocytes, exerting several systemic effects. Together with C-type NP (CNP), mainly expressed by endothelial cells, they also exert several paracrine and autocrine activities on the heart itself, contributing to cardiovascular (CV) health. In addition to their natriuretic, vasorelaxant, metabolic and antiproliferative systemic properties, NPs prevent cardiac hypertrophy, fibrosis, arrhythmias and cardiomyopathies, counteracting the development and progression of heart failure (HF). Moreover, recent studies revealed that a protein structurally similar to NPs mainly produced by skeletal muscles and osteoblasts called musclin/osteocrin is able to interact with the NPs clearance receptor, attenuating cardiac dysfunction and myocardial fibrosis and promoting heart protection during pathological overload. This narrative review is focused on the direct activities of this molecule family on the heart, reporting both experimental and human studies that are clinically relevant for physicians.

A 95-year-old patient with unexpected coronavirus disease 2019 masked by aspiration pneumonia: a case report

Background

Severe acute respiratory syndrome coronavirus-2 infection has become a pandemic disease (coronavirus disease 2019). The infection has moved from China to the rest of the world and Italy represents one of the most affected countries. Older adults are more susceptible to develop complications with the consequent highest mortality rates.

Case presentation

We report a case of a 95-year-old Caucasian woman affected by pneumonia, initially defined as common aspiration pneumonia in a bedridden patient with vascular dementia, which later turned out to be coronavirus disease 2019 pneumonia during the initial spread of severe acute respiratory syndrome coronavirus-2 in our district. Some features of a computed tomography scan of her chest and her clinical history with known dysphagia had led at first to a different diagnosis with a consequent exposure of health professionals to infectious risk in two distinct hospitals. In this case report, we describe the clinical/imaging features of coronavirus disease 2019 pneumonia and the diagnostic process that led to a correct diagnosis in a nonagenarian with multiple comorbidities.

Conclusions

This case report highlights both the possible pitfalls in diagnosing coronavirus disease 2019 pneumonia in very old patients with comorbidities and the greater than expected spread of the infection, even in individuals with reduced interpersonal contacts and no defined epidemiological link.

Sodium intake, large artery stiffness, and proteoglycans in the spontaneously hypertensive rat

Although the role of sodium in hypertension has been documented extensively, its effect on large arteries has not been well documented. We examined the effect of high-sodium (8%) diet and the diuretic indapamide (IND) on systemic hemodynamics and aortic wall structure and composition in collagen, elastin, and hyaluronan. Four groups of spontaneously hypertensive rats (SHR) were studied after 8 weeks: those on a normal diet (SHR), a high-sodium diet (SHR+NaCl), a normal diet with IND (SHR+IND), and a high-sodium diet with IND (SHR+NaCl+IND). Mean BP, which was not normalized with IND, was comparable for all groups. Systemic arterial compliance averaged 3.8, 2.5, 4.9, and 3.3 mL/mm Hg. 10(-3), respectively, for the SHR, SHR+NaCl, SHR+IND, and SHR+NaCl+IND groups (P<0.003 and <0.05 for NaCl and IND effects). Wall thickness increased only in the SHR+NaCl group (P<0.01). Aortic wall COL decreased from 16 116 in the SHR to 12 382 micrometer(2)/mm in the SHR+NaCl+IND (P<0.005) group. IND alone had no effect on elastin, but the elastin/collagen ratio was increased significantly. Aortic hyaluronan averaged 2343, 266, 3243, and 1052 micrometer(2)/mm, respectively, for the SHR, SHR+NaCl, SHR+IND, and SHR+NaCl+IND groups (P<0.0001 for NaCl and IND effects). Changes in systemic arterial compliance were significantly and positively correlated with aortic hyaluronan contents. Thus, high-sodium diet affects the structural and functional characteristics of large arteries independently of BP. A high-sodium diet, in addition to a diuretic regimen with IND, affects simultaneously aortic hyaluronan contents and large artery mechanical properties through pressure-independent mechanisms that remain to be defined.

Effects of combination of low doses of angiotensin-converting enzyme inhibitor and diuretics on renal function in spontaneously hypertensive rats: comparison between acute and chronic treatment

The goal of this study was to assess the effect of acute or chronic treatment with S5590, a combination of the angiotensin-converting enzyme inhibitor perindopril (0.76 mg/kg/day) and the diuretic indapamide (0.24 mg/kg/day) on renal function in spontaneously hypertensive rats with moderate renal injury. Renal function was evaluated in conscious rats by clearance methods using labelled inulin and PAH, after catheterisation of the carotid artery, jugular vein and bladder. Both acute and chronic treatment normalised renal vascular resistance, although the effect on blood pressure was more marked after chronic than after acute treatment. Although acute treatment with S5590 increased glomerular filtration rate and renal blood flow, chronic treatment did not affect these parameters. Diuresis and natriuresis were only slightly modified and the results suggest a marked renal vasodilatation. In conclusion, the maintenance of renal function after chronic treatment, in a setting of normalisation of arterial pressure, suggest that such a combined treatment may exert marked renal functional protective effects in hypertension.

Indapamide, a thiazide-like diuretic, decreases bone resorption in vitro

We recently showed that indapamide (IDP), a thiazide-related diuretic, increases bone mass and decreases bone resorption in spontaneously hypertensive rats supplemented with sodium. In the present study, we evaluated the in vitro effects of this diuretic on bone cells, as well as those of hydrochlorothiazide (HCTZ), the reference thiazide, and acetazolamide (AZ), a carbonic anhydrase (CA) inhibitor. We showed that 10(-4) M IDP and 10(-4) M AZ, as well as 10(-5) M pamidronate (APD), decreased bone resorption in organ cultures and in cocultures of osteoblast-like cells and bone marrow cells in the presence of 10(-8) M 1,25-dihydroxyvitamin D3 [1,25(OH)2D3]. We investigated the mechanism of this antiresorptive effect of IDP; IDP decreased osteoclast differentiation as the number of osteoclasts developing in coculture of marrow and osteoblast-like cells was decreased markedly. We then investigated whether IDP affected osteoblast-like cells because these cells are involved in the osteoclast differentiation. Indeed, IDP increased osteoblast-like cell proliferation and alkaline phosphatase (ALP) expression. Nevertheless, it did not modify the colony-stimulating factor 1 (CSF-1) production by these cells. In addition, osteoblast-like cells expressed the Na+/Cl- cotransporter that is necessary for the renal action of thiazide diuretics, but IDP inhibited bone resorption in mice lacking this cotransporter, so the inhibition of bone resorption and osteoclast differentiation did not involve this pathway. Thus, we hypothesized that IDP may act directly on cells of the osteoclast lineage. We observed that resorption pits produced by spleen cells cultured in the presence of soluble osteoclast differentiation factor (sODF) and CSF-1 were decreased by 10(-4) M IDP as well as 10(-5) M APD. In conclusion, in vitro IDP increased osteoblast proliferation and decreased bone resorption at least in part by decreasing osteoclast differentiation via a direct effect on hematopoietic precursors.

Pharmacokinetics of sustained and immediate release formulations of indapamide after single and repeated oral administration in healthy volunteers

The pharmacokinetics of a 2.5 mg immediate release (IR) formulation of indapamide was compared to a 1.5 mg sustained release (SR) formulation of indapamide after single and repeated oral administration dose using double blind randomised cross-over studies. In the first study, 12 subjects received a single dose of each treatment: IR fasted, SR fasted or with food. In the second study one tablet of either formulation was administered daily for one week at breakfast. In each study, blood samples were collected pre dose (Cmin) and up to 120 h after the last dose. Urine was collected over the dosing interval (24 h). Following a single oral administration the SR formulation had a lower dose-normalised Cmax compared to the IR formulation (17.6 +/- 6.3 vs. 39.3 +/- 11.0 ng x mL(-1), respectively), a much longer t(max) (12.3 +/- 0.4 vs. 0.8 +/- 0.3 h) and a greater t75 (15.3 +/- 6.1 vs. 1.8 +/- 1.4 h) but there were no differences in dose-normalised AUC (559 +/- 125 and 564 +/- 146 ng x h x mL(-1)) nor in t(1/2z) values (14.8 +/- 2.8 vs. 18.4 +/- 13.4 h). The SR formulation clearly demonstrated sustained release characteristics as compared to the IR formulation. Food co-administration had no effect on dose-normalised AUC for the SR formulation. After repeated administration, steady-state was achieved by day 5. The absorption rate of the SR formulation was lower and the 24 h peak-to-trough fluctuation was 4-fold lower compared to the IR formulation. After dose correction there wasno change in AUC, (726 +/- 207 and 690 +/- 183 ng x mL(-1) x h for SR and IR, respectively). The elimination parameters (t(1,2z), Ae(tau), and CLr) remained unchanged. The SR formulation showed sustained release of indapamide with a reduction in peak concentration, while steady-state level was not affected by formulations. The two formulations have the same bioavailability.

The effect of treatment with low dose ACE inhibitor and/or diuretic on coronary microvasculature in stroke-prone spontaneously hypertensive rats

Angiotensin II is considered to have angiogenic properties. Nevertheless, several authors reported an increase in coronary capillary density after treatment with ACE inhibitors. The aim of the present study was to evaluate the effect of treatment with low doses of ACE inhibitor perindopril, low doses of the diuretic indapamide, or a combination of the two on microvascular structure in hearts from stroke-prone spontaneously hypertensive rats (SHR-sp). Young adult male SHR treated with indapamide (0.24 mg/kg/day), perindopril (0.76 mg/kg/day), or both were compared with untreated animals after 8 or 14 weeks of treatment. Survival of SHR-sp was significantly increased after treatment. Only perindopril alone or in combination with indapamide significantly decreased blood pressure and cardiac mass. Treatment also significantly increased capillary and myocyte densities but arteriolar density tended to decrease. External and internal diameters significantly increased in treated animals while arteriolar thickness remained the same. Thus, thickness in vessels of the same size was the greatest in untreated animals, followed by indapamide- and perindopril-treated rats with the thinnest walls in rats with combined treatment, and the treatment resulted in a significant increase in the lumen to wall ratio. Capillary and arteriolar growth responses in treated animals seem to indicate that the two are independently regulated processes. Treatment with indapamide alone at this dosage did not significantly influence most responses but in combination with perindopril it strengthened the effect of perindopril.

Pharmacological properties of indapamide. Rationale for use in hypertension

Indapamide is a thiazide-related diuretic drug with antihypertensive properties. Its blood pressure-lowering action has been repeatedly demonstrated in acute as well as chronic conditions in various genetically and nongenetically determined forms of hypertension. In rats, the maximally effective oral dose is 3 mg/kg/24 h. The natriuretic effect of indapamide peaked at 3-fold at a dose of 1 mg/kg. In accordance with its antihypertensive properties, indapamide was shown to have excellent efficacy in protecting against target organ damage (heart, kidneys, brain). In addition to its natriuretic effect, it has been shown in several experiments that indapamide lowers the response to sympathetic nerve stimulation, exhibits calcium antagonist properties, enhances the production of prostacyclin, and limits the production of free radicals and of endothelium-dependent vasoconstrictor substances. These effects, even though they are observed at high indapamide concentrations and in a possibly species-dependent manner, may contribute to the beneficial properties of indapamide. The most recent data suggest that low doses of indapamide exert synergistic effects in combination with other antihypertensive drugs such as ACE inhibitors, the effects of which are influenced by the sodium status of the organism.

Galenic development and pharmacokinetic profile of indapamide sustained release 1.5 mg

In accordance with international guidelines recommending the use of low doses of antihypertensive agents, a new formulation of indapamide--indapamide sustained release (SR)--has been developed. Indapamide has been used worldwide for many years as an immediate release (IR) formulation at a dose of 2.5 mg. The IR formulation leads to plasma peaks of indapamide immediately after administration of the tablet. These peaks are responsible for possible unfavourable electrolyte or metabolic effects relating to indapamide blood concentrations. The SR formulation, by eliminating plasma peaks, allows a smoothing of the pharmacokinetic profile of indapamide. This new galenic formulation is based on a hydrophilic matrix tablet composed of a cellulose derivative, methylhydroxypropylcellulose (MHPC), and a binder, polyvinylpyrrolidone (povidone). The originality of the matrix lies in the percentages of MHPC and povidone, which permit a linear release in vitro of indapamide. After optimisation, the chosen ratio of these 2 constituents allowed the release of more than 70% of the dosage over 16 hours in a very reproducible manner. The 2 tested formulations (SR and IR) have the same bioavailability; however, the main pharmacokinetic parameters of the new SR 1.5 mg formulation, calculated after single and repeated administration, show a profile typical of an SR formulation, i.e. a lower maximum concentration (Cmax), a longer time to Cmax, and the same minimum concentration as the IR formulation. This new SR formulation, which allows a reduction in the daily dose of indapamide from 2.5 to 1.5 mg, leads to an improvement in its efficacy/tolerability ratio, thereby meeting the recommendations of the international guidelines for the treatment of essential hypertension.

Indapamide improves flow-induced dilation in hypertensive rats with a high salt intake

OBJECTIVE

Spontaneously hypertensive rats (SHR) are sensitive to a high salt intake and we investigated the question of whether flow-induced dilation is affected by this type of diet, as flow responses are especially sensitive to small changes in extracellular sodium concentrations.

METHODS

We evaluated the effects of a diuretic (indapamide, 1.5 mg/kg per day, 8 weeks) on four groups of SHR (n=42). One group was fed with a normal-salt diet (0.4%, control group, n=10), the second with a high-sodium diet (8%, n=12), the third with a high-sodium diet and indapamide (1.5 mg/kg per day, 8% salt, n=10) and the fourth group was fed with indapamide alone (1.5 mg/kg per day, n=10). The response to flow was studied in mesenteric resistance arteries (146+/-6.1 microm internal diameter, pressure 100 mmHg) cannulated in vitro in an arteriograph.

RESULTS

The increase in mean arterial pressure (from 186+/-4 to 218+/-6 mmHg; P < 0.01) and heart weight: body weight ratio (3.48+/-0.09 versus 4.34+/-0.1 mg/g; P< 0.01) caused by the high salt intake was prevented by indapamide. A high salt intake significantly decreased flow-induced dilation (6+/-0.8 versus 10.7+/-1.2 microm dilation with a flow of 160 microl/min; P< 0.05), while indapamide significantly prevented the decrease in flow-induced dilation in high-salt SHR. Indapamide had no significant effect on flow-induced dilation in mesenteric resistance arteries from SHR with a normal-salt diet.

CONCLUSIONS

Indapamide prevented the decrease in flow-induced dilation caused by a high-salt diet Therefore, indapamide might counteract the disturbance in sodium-sensitive flow sensor(s), through a diuretic effect.

The diuretic indapamide increases bone mass and decreases bone resorption in spontaneously hypertensive rats supplemented with sodium

Clinical and epidemiological studies suggest that thiazide diuretics can prevent bone loss and decrease the incidence of hip fractures. However, the mechanism of the effect of diuretics on bone is not clearly established. Indapamide (IDP), a sulfonamide diuretic related to thiazides, is used to treat hypertension. Sixty spontaneously hypertensive rats (SHRs) were divided into four groups and treated with or without IDP (1.5 mg/kg/day) during 8 weeks in the presence or absence of a high sodium load (8% NaCl supplementation in the diet). Sodium and calcium excretions were increased in the rats receiving the high sodium load (SHR + 8% NaCl) comparatively with control rats (SHR). IDP decreased and increased, respectively, calcium and sodium excretions. Serum parathyroid hormone (PTH) was unchanged in any group. Bone density was measured at the femur, tibia, and vertebrae, and bone morphometry was performed at the metaphysis of the femur to evaluate bone architecture. Rats fed a high sodium diet had an average 5.5% decreased bone density at every site except the femoral diaphysis. The trabecular bone volume was also decreased (SHR + 8% NaCl vs. SHR, 11.99+/-0.78 vs. 17.51+/-1.5%, p < 0.05). An increase in trabecular separation suggested that these changes were due to increased bone resorption. In the SHR + 8% NaCl + IDP group, IDP increased bone density and trabecular bone volume (SHR + 8% NaCl + IDP vs. SHR + 8% NaCl, 16.52+/-1.04 vs. 11.99+/-0.78%, p < 0.05). Trabecular separation and pyridinoline/creatinine excretion (SHR + 8% NaCl + IDP vs. SHR + 8% NaCl, 136.39+/-9.62 vs. 195.18+/-22.34 nmol/mmol, p < 0.05) were also decreased by IDP. These results show that in rats receiving a high sodium diet, IDP can reverse sodium-induced bone loss and increased bone resorption independently of changes in serum PTH.

High sodium intake decreases pressure-induced (myogenic) tone and flow-induced dilation in resistance arteries from hypertensive rats

High sodium intake has been associated with a higher blood pressure level. Resistance arteries are the main determinants of blood pressure. They are largely regulated by pressure (tensile stress)-induced tone (myogenic tone, MT) and by flow (shear stress)-induced dilation (FD). Thus, we studied the effect of NaCl (8%) intake for 8 weeks on FD and MT in mesenteric resistance arteries of spontaneously hypertensive rats. Arteries were cannulated and mounted in an arteriograph. Intraluminal diameter was measured continuously. High NaCl intake increased mean arterial pressure (186+/-5 to 217+/-6 mm Hg, P<0.01). Passive arterial diameter ranged from 112+/-6 to 185+/-9 microm (pressure from 25 to 125 mmHg, no effect of NaCl). MT developed in response to pressure (tone from 89+/-1% to 83+/-3% of passive diameter, 25 to 125 mm Hg). High NaCl intake significantly decreased MT (89+/-1% versus 83+/-3% of passive diameter when pressure was 125 mm Hg, P<0.023). High NaCl intake also decreased FD (6.5+/-0.8 versus 10+/-1.3 microm dilation under a pressure of 100 mm Hg and a flow rate of 160 microL/min, P<0.012). Thus, high salt intake decreased both flow (shear stress)-induced dilation and pressure (tensile stress)-induced tone in mesenteric resistance arteries. These findings might reflect attenuation by NaCl of flow and pressure mechanosensor processes.

Antioxidant properties of indapamide, 5-OH indapamide and hydrochlorothiazide evaluated by oxygen-radical absorbing capacity and electron paramagnetic resonance

The aim of these experiments was to investigate the radical scavenging properties of three diuretics: indapamide (IND) and its major metabolite, 5-OH indapamide (5-OH IND), compared to a reference diuretic, hydrochlorothiazide (HTZ). Electron Paramagnetic Resonance (EPR) was used to determine the scavenging abilities of these compounds on enzymatically produced superoxide radical anion, with 5,5-dimethyl-1-pyrroline N-oxide (DMPO) used as a spin-trap. These experiments revealed that IND and specially 5-OH IND were effective superoxide radical anion scavengers at 0.2 mg/ml. In the second part of these studies, allophycocyanin was used as an indicator of free radical mediated protein damage. In the assay, 2,2'-azobis(2-amidinopropane) hydrochloride (AAPH) was used as a peroxyl radical generator, Trolox (a water-soluble analogue of vitamin E) as a control standard, and the loss of allophycocyanin fluorescence was monitored. The antioxidant effects of the diuretics were expressed in oxygen-radical absorbing capacity (ORAC), where one ORAC unit equals the net protection produced by 1 microM Trolox. HTZ showed no protection up to 100 microM final concentration, whereas IND and 5-OH IND showed linear correlation with respect to concentration when expressed in ORAC units: 5-OH IND induced the highest protection against peroxyl radical. The above observations suggested that IND and 5-OH IND are potent radical scavengers, with the metabolite 5-OH IND having a superior antioxidant potency than IND. By contrast, HTZ had no effect. These radical scavenging properties of 5-OH IND may be of clinical interest for vascular protection and may help to protect the heart from oxidative injury.

Effects of indapamide on Ca2+ entry into vascular smooth muscle cells

Part of the antihypertensive action of indapamide has been attributed to a direct inhibitory action on Ca2+ entry into vascular smooth muscle cells. The present study has been performed to identify the possible mechanisms involved. To this end the effect of indapamide on intracellular Ca2+ activity - [Ca2+]i - has been tested under control conditions and under conditions known to increase [Ca2+]i such as osmotic cell swelling (mimicking mechanical stress), depolarization (increase of extracellular K+ concentration) and oxidative stress (H2O2). Indapamide (10 micromol/l) was without effect on control [Ca2+]i, but significantly blunted the increase of [Ca2+]i following potassium-induced depolarization or following osmotic cell swelling. It did not significantly modify the increase of [Ca2+]i induced by H2O2. The effects on cell membrane potential induced by increased [K+], osmotic cell swelling, or H2O2 were not significantly modified by indapamide (10 micromol/l). Voltage-gated Ca2+ currents were not significantly modified by 10 micromol/l indapamide, but were significantly reduced by 100 micromol/l and blunted by 1 mmol/l. In conclusion, indapamide at high concentrations (100 micromol/l) inhibits voltage-gated Ca2+ channels, an effect which blunts the increase of [Ca2+]i during depolarization of the cell membrane at increased extracellular [K+] or osmotic stress. Whether these effects at high concentrations of indapamide are relevant to the antihypertensive action, however, cannot be established from these in vitro studies.

Fixed-dose combination of perindopril with indapamide in spontaneously hypertensive rats: haemodynamic, biological and structural effects

OBJECTIVE

The present study was designed to test the effects of chronic combined treatment with low doses of an angiotensin converting enzyme inhibitor (perindopril) and of the diuretic indapamide in spontaneously hypertensive rats (SHR).

METHODS

Adult SHR were treated with placebo or increasing doses of the combination of the drugs (0.3, 1 and 3 mg/kg per day; ratio of doses 0.32). In a separate set of experiments, the effects of the drugs combined (1 mg/kg per day) was compared with those induced by each drug alone.

RESULTS

The drug combination dose-dependently decreased systolic blood pressure and its hypotensive effect was more marked than those induced by each treatment administered alone (untreated 208 +/- 5 mmHg, indapamide 185 +/- 5 mmHg, perindopril 150 +/- 3 and the combination 123 +/- 7 mmHg). A 12-week treatment with the drug combination (1 mg/kg per day) was not accompanied by any change in diuresis or urinary excretion of Na or K. The same treatment decreased cardiac hypertrophy and collagen. At the vascular level, the drug combination decreased aortic, carotid and femoral media cross-sectional areas, as well as aortic and carotid collagen density. This latter effect was accompanied by a significant increase in carotid artery compliance assessed in vivo at constant pressure. Finally, in isolated aortae, chronic combined drug treatment was associated with an increased basal release of nitric oxide and a decrease in the hypertension-induced endothelium-dependent contractions in response to acetylcholine.

CONCLUSION

These experiments suggest that chronic combined treatment with low doses of an angiotensin converting enzyme inhibitor and a diuretic such as indapamide may be of value in the treatment of hypertension.

Arterial smooth muscle cell phenotype in stroke-prone spontaneously hypertensive rats

The aim of this study was to determine the phenotype of smooth muscle cells in the arteries of chronically hypertensive animals and to analyze the effects of treatments known to increase the survival of the animal without a clear effect on its hypertensive state. Stroke-prone spontaneously hypertensive rats (SHRSP) kept on a 1% sodium drinking solution were untreated or treated with one of two diuretics, indapamide (3 mg/kg per day) or hydrochlorothiazide (20 mg/kg per day), from 6 to 13 weeks of age. Phenotype was characterized by the immunolabeling of arteries with antibodies raised against a cellular form (EIIIA) of fibronectin, alpha-smooth muscle actin, and nonmuscle myosin. We demonstrated that phenotypes of smooth muscle cells of the SHRSP differ from those found in Wistar-Kyoto rats. The difference in phenotype is specific for the vessel type: ie, an increased expression of nonmuscle myosin in the aorta and of both EIIIA fibronectin and nonmuscle myosin in the coronary arteries. The two diuretics (1) had no effect on blood pressure, (2) prevented or did not prevent the increase in medial thickness, and (3) prevented changes in both smooth muscle cell phenotype and ischemic tissular lesions. Taken together, the results suggest that in SHRSP the changes in the phenotype of smooth muscle cells and the thickness of arteries are unrelated events. We propose that the maintenance of the contractile phenotype of the arterial smooth muscle cells could be an essential parameter involved in the prevention of the deleterious consequences characteristic of a severe hypertensive state.

5-HT1A receptor agonists prevent in rats the yawning and penile erections induced by direct dopamine agonists

The new compound (+) S-20499, an amino chromane derivative (8[-4[N-(5-methoxychromane-3yl)N-propyl]aminobutyl] azaspiro[4-5] décane-7,9 dione), is a high affinity full 5-HT1A agonist. We have investigated its effects on dopaminergic transmission. (+) S-20499 displayed a 10(-8) M affinity for D2 dopamine (DA) receptors, 100 fold lower than for 5-HT1A receptors. The hypothermic effect of the drug was reversed by haloperidol in mice, suggesting that it behaves as a direct dopamine agonist. However, increasing doses of (+) S-20499 induced neither yawning nor penile erections, which constitute characteristic responses of direct DA agonists administered at low doses. In addition, (+) S-20499 prevented the apomorphine (100 micrograms/kg SC) induced yawning and penile erections. This inhibition appears to result from the stimulation of 5-HT1A receptors since it is an effect shared by both buspirone (from 5 mg/kg) and 8-OH-DPAT (from 0.10 mg/kg). In addition, when rats are treated with the 5-HT1A receptor antagonist tertatolol (2-5 mg/kg; SC), increasing doses of (+) S-20499 elicit the expected yawns and penile erections. It is concluded that the 5-HT1A agonist property opposes to that of D2 dopamine receptor stimulation with regard to yawning and penile erections.

Inhibition of angiotensin I-converting enzyme with S 9490: biochemical effects, interspecies differences, and role of sodium diet in hemodynamic effects

S 9780, the diacid form of S 9490, inhibited guinea pig plasma angiotensin-converting enzyme (ACE) by 50% (IC50) at a concentration of 2.4 +/- 0.1 nM. A Ki of 1.2 nM was obtained for S 9780 (Dixon-Webb plot) with angiotensin I as a substrate. In rabbits, rats, cats, guinea pigs, and dogs, S 9780 MK 422, S 9490, and MK421 decreased, in a dose-dependent manner, the pressor response to angiotensin I. The rabbit and the rat were the most sensitive species, with ID50 values, respectively, of 2.7 +/- 0.4 and 5.9 +/- 0.3 micrograms/kg i.v. for S 9490 and 1.2 +/- 0.2 and 2.6 +/- 0.8 micrograms/kg i.v. for S 9780. S 9490 induced a dose-dependent decrease in serum ACE activity in rabbits (0.6-20 micrograms/kg i.v.) and guinea pigs (10-100 micrograms/kg i.v.). In conscious rats and dogs S 9490 (0.03-1 mg/kg p.o.) induced a long-lasting inhibition of the angiotensin I-induced pressor response; 40% inhibition was recorded in dogs, 24 h after 1 mg/kg p.o. S 9490 (0.03-0.1 mg/kg i.v.) potentiated the increase in femoral blood flow induced by bradykinin injected into the femoral artery of dogs. In anesthetized dogs, mean blood pressure and heart rate were not changed after sodium restriction, but the cardiac output was markedly decreased. S 9490 (0.1-1 mg/kg i.v.) decreased mean blood pressure both in sodium-restricted and sodium-repleted pentobarbital-anesthetized dogs. However, the lowering effect was more pronounced in sodium-restricted dogs. S 9490 (3 mg/kg p.o.) did not change mean blood pressure in conscious dogs maintained on normal-sodium diet but decreased mean blood pressure in conscious sodium-restricted dogs. Plasma renin activity (PRA) and plasma aldosterone concentration were strongly enhanced in conscious dogs maintained on low-sodium diet.(ABSTRACT TRUNCATED AT 250 WORDS)