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Biomedical subjects

J Sassard

Publications and source records attributed to J Sassard.

At least 253 records · Page 14Linked to original sources
PubMedDate not supplied

Pharmacokinetics of nalidixic acid associated with sodium citrate.

A pharmacokinetic study of sachets containing nalidixic acid (0.66 g) associated with sodium citrate (3.75 g)--NSC--was carried out in 10 healthy volunteers in order to determine the influence of the urine alcalinization due to sodium citrate on the elimination of nalidixic acid (NA) and its 7-hydroxy (HNA) and 7-carboxy (CNA) derivatives. Urine alcalinization enhanced markedly the urinary excretion of HNA, but not of NA and CNA. The urinary concentrations of bacteriologically active compounds--NA + HNA--remained above five times their minimum inhibitory concentration for 10 h following each dose. After a 3-day treatment using NSC three times daily there was no significant accumulation of NA and derivatives in the plasma and no significant change in their kinetics. Finally, from a pharmacokinetic viewpoint, the daily administration of 3 sachets of NSC each containing 0.66 g of NA seems valuable in the treatment of urinary tract infections.

Adult↗
PubMedDate not supplied

Specific decrease of secretin/VIP-stimulated adenylate cyclase in the heart from the Lyon strain of hypertensive rats.

The cardiac adenylate cyclase activity of genetically hypertensive rats from the Lyon strain (LH) was compared to that of Lyon normotensive rats (LN) and that of low blood pressure Lyon rats (LL). The major finding was a 30-35% decrease of secretin- and VIP-stimulated adenylate cyclase activity in cardiac membranes of LH rats that was already obvious in 5 week-old prehypertensive animals: this alteration was apparently specific for the cardiac secretin/VIP-stimulated adenylate cyclase activity, the same activity in membranes from brain, anterior pituitary, and liver being similar in LH, LN and LL rats. It is tempting to conclude that a selective alteration of functional cardiac secretin/VIP receptors in LH rats reflects a local hyperactivity of the sympathetic adrenergic system.

Adenylyl Cyclases↗
PubMedDate not supplied

Plasma lipids in genetically hypertensive rats of the Lyon strain.

Of the four standardized strains of genetically hypertensive rats, only the Lyon hypertensive rats spontaneously exhibit a higher body weight than their normotensive controls. In order to determine if this increased body weight is associated with alterations in the lipid metabolism, plasma triglycerides (TG), phospholipids (PL), total cholesterol (TPC), and high-density lipoprotein cholesterol (CHDL) were followed in Lyon hypertensive (LH), normotensive (LN), and hypotensive (LL) male rats between 5 and 32 weeks of age. TG were stable with age in LL and LN but increased in LH rats. PL decreased in LL, remained stable in LN, but increased with age in LH rats. TPC and CHDL were stable in LL and LN and increased with age in LH rats. Plasma lipids were not related to the blood pressure level, but were positively related to the body weight in the hypertensive strain. Thus, starting at the age of 5 weeks, LH rats exhibit spontaneously a significant increase in blood pressure, body weight, and plasma lipid concentrations.

Aging↗
PubMedDate not supplied

Cytochrome P-450-dependent arachidonate metabolites and renal functions in the Lyon hypertensive rat.

1. The present work aimed to assess the role of cytochrome P-450 (CP-450) metabolites of arachidonic acid such as epoxy-eicosatrienoic (EET) and hydroxyeicosatetraenoic acids (HETE) in the renal vasoconstriction and decreased natriuresis exhibited by genetically hypertensive (LH) rats of the Lyon strain. 2. The experiment was performed on single-pass isolated perfused kidney preparations from 8-week-old male LH rats and their low blood pressure (LL) controls. The effects of miconazole (an inhibitor of the formation of EET) and of 17-octadecynoic acid (17-ODYA, an inhibitor of both EET and HETE synthesis) were studied before and after stimulation of the kidneys with two noradrenaline (NA) infusions (65 and 110 nmol/L). 3. Unstimulated LH kidneys (n = 12) differed from LL (n = 12) by increased vascular resistance (RVR) and decreased glomerular filtration rate and urinary sodium excretion (UNaV). 4. Miconazole (1 mumol/L) did not change the functions of LH and LL unstimulated kidneys, but blunted the vasoconstrictor response to NA (110 nmol/L), the difference being significant in LH kidneys only (1.7 +/- 0.2 vs 3.6 +/- 1.2 mmHg/mL per min per g; P < 0.05). 5. Addition of 17-ODYA (3 mumol/L) to miconazole did not modify RVR in LH and LL kidneys or the response to NA infusion. On the contrary, it increased UNaV, the differences being significant in LH kidneys only (22.9 +/- 1.4 vs 17.5 +/- 1.4 mumol/min per g; P < 0.05 after NA 110 nmol/L). 6. It is suggested that EET may contribute to the elevated RVR and HETE to the reduced ability to excrete sodium, of LH kidneys.

Animals↗
PubMedDate not supplied

Collagen I and III and mechanical properties of conduit arteries in rats with genetic hypertension.

Conduit arteries of hypertensive rats are thicker and stiffer than those of normotensive controls. The possible role played by collagen type I and II subtypes in the mechanism of arterial stiffness remains unknown. The carotid and aortic arterial wall of rats of Japanese (Wistar-Kyoto and spontaneously hypertensive rats) and Lyon (normotensive and hypertensive rats) origin were studied. The stiffness of the carotid wall material (ultrasound), the histomorphometry of the aortic wall with the content in collagen I and III subtypes and their corresponding mRNA were analyzed. Independently of hypertension, the Japanese group differed from the Lyon group by a stiffer carotid wall material at any given value of wall stress; a lesser degree of aortic hypertrophy with a higher percentage of elastin, and a higher density of collagen III but not of collagen I. All other hemodynamic and histomorphometric parameters were affected by both the origin of the rats (Japanese vs. Lyon) and the presence of hypertension. Large artery stiffness in genetically hypertensive rats was not only influenced by hypertension itself, but also by differences in the contents of collagen subtypes which are also found in their corresponding normotensive controls.

Animals↗
PubMedDate not supplied

Urinary prostaglandins in the Lyon strains of hypertensive, normotensive, and low blood pressure rats.

A longitudinal study of the urinary excretion of prostaglandins (PGs) E and F alpha was performed in simultaneously selected hypertensive (LH), normotensive (LN), and low blood pressure (LL) female rats of the Lyon strains aged from 5 to 45 weeks. The urinary excretion of PGE did not significantly differ between LL and LN rats whereas in LH rats it was found to be significantly lower than that of LN or LL rats starting at the age of 32 weeks. The urinary excretion of PGF alpha was significantly reduced in both LL and LH rats; however, this decrease was more marked in LH than in LL animals and, from 9 weeks of age, the urinary PGF alpha were significantly lower in LH than in age-matched LL rats. In addition, both PGE and PGF alpha were found to be significantly and negatively related to the systolic blood pressure level in LH rate (r = -0.56, n = 58, p less than 0.001 for PGE; and r = -0.78, n = 58, p less than 0.001 for PGF alpha) but not in LN of LL animals. In conclusion, it seems unlikely that renal PGs could play a primary role in the spontaneous hypertension observed in the Lyon strain of rats.

Animals↗
PubMedDate not supplied

Genetics of blood pressure and associated phenotypes in the Lyon rat.

The Lyon model of genetic hypertension is made of 3 simultaneously selected strains, one hypertensive (LH) one normotensive (LN) and one with low blood pressure (LL). Since LN and LL rats exhibit the same blood pressure (BP) LH rats can be compared to 2 genetically pure and different strains of control animals. This proved to be useful for the interpretation of the data of molecular genetic studies, eg: since the renin gene was polymorphic between LH and LN but not between LH and LL rats it could be suggested that the reported linkage of renin gene polymorphism and high BP in F2 hybrids may involve another closely located gene. LH rats associate to high BP spontaneous increases in body weight, plasma cholesterol, fibrinogen and hematocrit. During the phenotyping of F1 and F2 hybrids from a LH x LN cross and of back-crosses to LH rats it was observed that all these phenotypes were recessive, except the large body weight of LH rats which was dominant and, thus, unrelated to BP. On the contrary, BP was significantly related to plasma cholesterol in both F2 and back-cross rats and, in this latter cohort, plasma cholesterol correlated also with fibrinogen and hematocrit levels. Therefore, the study of the Lyon rat may be useful not only to determine the genes involved in hypertension but also those which contribute to other cardiovascular risk factors such as elevated fibrinogen and hematocrit.

Animals↗
PubMedDate not supplied

Renin secretion in Lyon hypertensive rats.

In genetically hypertensive rats of Lyon strain (LH), both development and maintenance of hypertension are extremely sensitive to the chronic blockade of the renin-angiotensin system. However, LH rats exhibit a low renin secretory profile as indicated by (1) low basal plasma renin concentration; (2) blunted renin responses to reductions of renal perfusion pressure and beta-adrenoceptor stimulation both in vitro (isolated perfused kidney) and in vivo (conscious rat). None of the latter abnormalities are corrected by chronic sodium deprivation or when hypertension is prevented by hydralazine or perindopril treatment. Future studies will therefore have to elucidate the 'renin paradox' in LH rats.

Adrenergic beta-Agonists↗