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Full-Text Articles in Physiology
Maturational Changes In Myosin Light Chain Kinase Activity In Ovine Carotids, Elisha Raju Injeti
Maturational Changes In Myosin Light Chain Kinase Activity In Ovine Carotids, Elisha Raju Injeti
Loma Linda University Electronic Theses, Dissertations & Projects
Vascular reactivity changes dramatically during postnatal maturation due in large part to developmental changes in myofilament calcium sensitivity. Recent findings suggest that reactivity of the thick filament component of calcium sensitivity is upregulated in fetal compared to adult arteries. In light of these findings, the present study tests the hypothesis that upregulation of fetal thick filament reactivity is due to upregulation of myosin light chain kinase (MLCK) activity. To test this hypothesis, MLCK abundance and its activity is measured in intact arteries. The results indicate that MLCK abundance is 6.03 ± 0.96 fold greater in adult than in fetal arteries. …
Maturational Changes In Cerebrovascular Thick- And Thin-Filament Regulation, Renan Joel Sandoval
Maturational Changes In Cerebrovascular Thick- And Thin-Filament Regulation, Renan Joel Sandoval
Loma Linda University Electronic Theses, Dissertations & Projects
The present study focused on the main hypothesis that age-related changes in myofilament Ca2+ sensitivity involve simultaneous changes in the relations between cytosolic Ca2+ transients, myosin phosphorylation, and force development. To define the effects of late fetal and early postnatal maturation, parallel experiments were carried out using cerebral arteries from both term lamb fetuses (140-141 days of gestation) and nonpregnant adult sheep. Fetal and adult cerebral arteries were stimulated by either mechanically, electromechanically, and/or pharmacomechanically-induced contractions, and the relations of cytosolic Ca2+, MLC phosphorylation, and contractile tensions were measured. These measurements allowed for stimulus and age-dependent …
Regulation Of Alpha-1-Adrenoceptor-Mediated Contractions Of The Uterine Artery By Pkc, Hongying Zhang
Regulation Of Alpha-1-Adrenoceptor-Mediated Contractions Of The Uterine Artery By Pkc, Hongying Zhang
Loma Linda University Electronic Theses, Dissertations & Projects
Pregnancy is associated with a significant decrease in uterine vascular tone and a striking increase in uterine blood flow, which ensures normal fetal development. Multiple mechanisms are involved in the adaptation of uterine artery contractility during pregnancy. Both protein kinase C (PKC) and activation of ai-adrenoceptors play important roles in the regulation of uterine artery contractility. In addition, PKC mediates the pregnancyassociated decrease in myogenic tone of the uterine artery, and interacts with ajadrenoceptors leading to modulation of ai-adrenoceptor-mediated contractions of vascular smooth muscle. Yet, whether or to what extent PKC regulates ai-adrenoceptormediated contractions of the uterine artery and their …
Interaction Between Adrenergic And Nitric Oxide-Releasing Nerves In Cerebral Arteries, Emmanuel Ngu Mbaku
Interaction Between Adrenergic And Nitric Oxide-Releasing Nerves In Cerebral Arteries, Emmanuel Ngu Mbaku
Loma Linda University Electronic Theses, Dissertations & Projects
Of all body tissues, the brain is the least tolerant of ischemia so much that interruption of cerebral blood flow by 5 sec can cause syncope, with irreversible tissue damage if the ischemia last a few minutes. In this respect, the body has an imperative duty of ensuring constant and adequate blood supply to the brain. It does so through a series of intrinsic and extrinsic control factors of which adrenergic and nitric oxide-releasing nerves are components. My research examined the interaction between these two nerve-types with emphasis on the mechanisms involved as well as on changes in their functions …
Effects Of Portuguese Man-Of-War (Physalia Physalis) Venom On Isolated Rabbit Atria, Wayne R. Bonlie
Effects Of Portuguese Man-Of-War (Physalia Physalis) Venom On Isolated Rabbit Atria, Wayne R. Bonlie
Loma Linda University Electronic Theses, Dissertations & Projects
The cardiac effects of Portuguese man-of-war venom were studied using isolated atria from rabbits. Venom added (7.1 µg protein/ml) to the bath solution stimulates heart rate 120% (P < 0.01) and increases contraction amplitude 308% (P < 0.001). Both effects are dependent on bath concentrations of venom and calcium. The increase in contraction amplitude is significantly attenuated by diltiazem (0.8 µM) and atenolol (10 µM). Atenolol, a β1-adrenergic antagonist, completely blocks the increase in heart rate. Dantrolene (10 µM) did not significantly block the venom's effects. Ryanodine binding increases in the presence of venom showing that the venom is not in competition for calcium channels on the sarcoplasmic reticulum. These results suggest that the venom acts on the sarcolemma to increase calcium permeability, thereby causing an increase in contraction amplitude and possibly causing β1-adrenergic stimulation.
Molecular Mechanisms Of Physalia Physalis Venom Modulation Of Cardiac And Vascular Functions, Eva Luo
Molecular Mechanisms Of Physalia Physalis Venom Modulation Of Cardiac And Vascular Functions, Eva Luo
Loma Linda University Electronic Theses, Dissertations & Projects
Portuguese man-of-war (Physalia physalis)venom has profound effects on the cardiovascular system of man and animals. The venom produces vascular relaxation in norepinephrine precontracted, intact rabbit femoral arterial rings by stimulating vasodilatory prostaglandin synthesis in the endothelium. This action does not depend on endotheliumderived relaxing factor (EDRF). P. physalis venom produces a vascular constriction on KC1 depolarized, intact rings. This is completely inhibited by dibenzyline and yohimbine. Increased membrane permeability to calcium may be involved in direct vascular smooth muscle stimulation. The venom has a positive inotropic effect on rat atrial preparations, which is intensified by increased extracellular calcium concentration. …
Mast Cell Histamine Release Induced By Portuguese Man-Of-War (Physalia) Venom, A. Lester Flowers
Mast Cell Histamine Release Induced By Portuguese Man-Of-War (Physalia) Venom, A. Lester Flowers
Loma Linda University Electronic Theses, Dissertations & Projects
Richet and Portier studied the immunization of dogs against attenuated toxic extracts of the sea anemone and showed that, when given secondary injections of sublethal amounts of native toxic extracts, the dogs experienced severe pruritus and insensitivity followed by death. They called this increased sensitivity to the toxins, anaphylaxis. Richet and Portier, and later Jacques and Schachter, and Uvnäs also studied the direct pruritic and histamine releasing effects of cnidarian (e.g. Physalia, Actinia, Cyanea), toxic extracts. While the anaphylactic effect, discovered by Richet and Portier, has been extended by numerous studies to provide the foundation of our current knowledge of …