PubMed Health⌕ Search
Home/Archive/PubMed

PubMed · 11821710

Nitric oxide synthase upregulation and the predelivery blood pressure decrease in spontaneously hypertensive rats.

Heinrich Gompf·Friedrich C Luft·Ingo Morano
View original source ↗Export metadata ↓

Abstract

OBJECTIVE: The pregnant spontaneously hypertensive rat (SHR) exhibits a decrease in arterial blood pressure shortly before delivery; however, the mechanisms are unknown. Nitric oxide may be involved. DESIGN: Blood pressure in stroke-prone SHR (SHRSP) and Wistar-Kyoto control rats (WKY) was telemetrically measured. Four groups were studied: pregnant and non-pregnant WKY and SHRSP rats, respectively. Mean blood pressure in pregnant SHRSP rats decreased from 148 +/- 2 mmHg at conception to 120 +/- 4 mmHg at day 15, compared to 112 +/- 1 mmHg in pregnant WKY rats. At delivery, we determined the vasodilatory responses of isolated preconstricted aortic strips. RESULTS: Vasodilatory responses from late-term SHRSP rats were significantly greater following acetylcholine than either those from non-pregnant SHRSP or pregnant and non-pregnant WKY rats (acetylcholine IC50: 5, 22.8, 398, 1000 nmol/l, respectively), while contractile responses to increasing doses of norepinephrine were not different. Similar results were obtained with substance P. Indomethacin had no effect on the relaxation responses. Relaxation in response to sodium nitroprusside was not different in the groups. Western blot analysis showed that endothelial nitric oxide synthase (eNOS) levels were significantly increased in the pregnant SHRSP vessels compared to non-pregnant SHRSP, pregnant WKY, and non-pregnant WKY vessels. CONCLUSION: Increased NOS may explain the blood pressure decrease during late pregnancy in genetically hypertensive rats.

Explore related subjects

AcetylcholineAnimalsBlood PressureDisease Models, AnimalDose-Response Relationship, DrugEndothelium, VascularFemaleMuscle RelaxationNitric Oxide SynthaseNorepinephrinePregnancyRatsRats, Inbred SHRRats, Inbred WKYTime FactorsUp-RegulationVasoconstrictor AgentsVasodilator AgentsComparative StudyJournal ArticleResearch Support, Non-U.S. Gov't

Keep this discovery

Explore connections, maps & timelines

BibTeXRIS

Heinrich Gompf, Friedrich C Luft, Ingo Morano. 2002. Nitric oxide synthase upregulation and the predelivery blood pressure decrease in spontaneously hypertensive rats.. https://doi.org/10.1097/00004872-200202000-00015

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related citations

PubMed2003

Cholinergic neuropathology in a mouse model of Alzheimer's disease.

Transgenic mice overexpressing mutant human amyloid precursor protein (PDAPP mice) develop several Alzheimer's disease (AD)-like lesions including an age-related accumulation of amyloid-beta (Abeta)-containing neuritic plaques. Although aged, heterozygous PDAPP mice also exhibit synaptic and glial cell changes characteristic of AD pathology, no evidence of widespread neuronal loss has been observed. The present study sought to determine whether homozygous PDAPP mice, which express very high levels of Abeta peptide, exhibit AD-like cholinergic degenerative changes, and whether the changes parallel the deposition of Abeta plaques. Mice were examined at 2 and 4 months and at 1 and 2 years of age. There was an age-related increase in the density of Abeta plaques in the cortex and hippocampus of the PDAPP animals; at 4 months of age there were very few plaques, and at 2 years there was a very high density of plaques. There was an age-related reduction in the density of cholinergic nerve terminals in the cerebral cortex; at 2 months there was a normal density of nerve terminals, but as early as age 4 months there was an approximately 50% reduction. However, at age 2 years there was no difference in the number or size of basal forebrain cholinergic somata compared with 2-month-old PDAPP mice. These data indicated that the homozygous PDAPP mouse exhibits cholinergic nerve terminal degenerative pathology and that the cortical neurodegenerative changes occur before the deposition of Abeta-containing neuritic plaques.

Acetylcholine↗
PubMed2003

Octopaminergic modulation of synaptic transmission between an identified sensory afferent and flight motoneuron in the locust.

The role of the biogenic amine octopamine in modulating cholinergic synaptic transmission between the locust forewing stretch receptor neuron (fSR) and the first basalar motoneuron (BA1) was investigated. The amines 5-hydroxytryptamine (5-HT, serotonin) and dopamine were also studied. Bath application of octopamine, 5-HT, and dopamine at concentrations of 10(-4) M reversibly decreased the amplitude of monosynaptic excitatory postsynaptic potentials (EPSPs) evoked in BA1 by electrically stimulating the fSR axon. These effects occurred without any detectable change in either input resistance or membrane potential of BA1. The amines also reversibly decreased the amplitude of responses to acetylcholine (ACh) pressure-applied to the soma of BA1. The muscarinic antagonist scopolamine (10(-6) M) had no significant effect on the octopamine-induced decrease in ACh responses. These observations suggest that these amines potentially could physiologically depress cholinergic transmission between fSR and BA1, at least in part, by altering nicotinic rather than muscarinic cholinergic receptor function. Although the octopaminergic agonists naphazoline and tolazoline both mimicked the actions of octopamine, the receptor responsible for octopamine-mediated modulation could not be characterized since amine receptor antagonists tested on the preparation had complex actions. Confocal immunocytochemistry revealed intense octopamine immunoreactivity in the anterior lateral association center, thus confirming the presence of octopamine in neuropil regions containing fSR/BA1 synapses and therefore supporting a role for this amine in the modulation of synaptic transmission between the fSR and BA1. 5-HT-immunoreactivity, conversely, was concentrated within the ventral association centers; very little staining was observed in the dorsal neuropil regions in which fSR/BA1 synapses are located.

Acetylcholine↗
PubMed2003

Contractile cochlear frame in the gecko Teratoscincus scincus.

It is generally accepted that the cartilaginous frame of the reptilian cochlea has only a passive supportive function. In this study, a ribbon of contractile tissue was revealed within the cartilaginous frame of the cochlea of the gecko Teratoscincus scincus. It consisted of tightly packed cells and received an extensive blood supply. The cytoplasm of the cells was filled with cytoskeletal filaments 5-7 nm thick as revealed by electron microscopy. Isolated tissue permeabilized with Triton X-100 or glycerol reversibly contracted in the presence of ATP. Noradrenaline caused slow relaxation of the freshly isolated tissue placed in artificial perilymph. We suggest that slow motility of the contractile tissue may adjust passive cochlear mechanics to sounds of high intensities.

Acetylcholine↗