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Signaling Mechanisms For Muscarinic Receptor-Mediated Coronary Vasoconstriction In Isolated Rat Hearts, Yi Zhang
Electronic Theses and Dissertations
The signaling mechanisms for muscarinic receptor-mediated vasoconstriction in coronary resistance arteries were studied in KCl-arrested isolated rat hearts perfused at a constant flow rate. The cholinergic agonists acetylcholine and bethanechol were given by bolus injection or constant infusion. The coronary vascular resistance was monitored by measuring the changes in perfusion pressure. The selective muscarinic agonist bethanechol caused a similar vasoconstrictor response as ACh, but with less potency and efficacy. Bolus injection of bethanechol evoked a phasic vasoconstriction in a dose-dependent manner, while infusion of bethanechol evoked a tonic vasoconstriction without producing tachyphylaxis. Coronary vascular responses to bethanechol were further examined …
The Ecology And Life History Of The Mexican Tetra, Astyanax Mexicanus, (Teleostei: Characidae) In The Lower Rio Grande Valley, Texas, Mario Estrada
The Ecology And Life History Of The Mexican Tetra, Astyanax Mexicanus, (Teleostei: Characidae) In The Lower Rio Grande Valley, Texas, Mario Estrada
Theses and Dissertations - UTB/UTPA
The Mexican tetra has been found to migrate from shallow waters in the spring and summer months into deeper waters during the winter months when temperatures are too cold for their survival. This fish is omnivorous with insect material being the major source of food. Its food types include green algae, nematoceran larvae, hemipterans, coleopterans, hymenopterans, dipterans, ostracods, fish eggs and amphipods. Furthermore, size classes showed that the Mexican tetras reached their largest size at the River site and smaller sizes at the Bridge and Gate sites and apparently breed year round. They are capable of producing from 300 to …
Sucrose Metabolism In Two Saccharum Species, Monica Ida Valdez-Garza
Sucrose Metabolism In Two Saccharum Species, Monica Ida Valdez-Garza
Theses and Dissertations - UTB/UTPA
S. officinarum is a thick-stemmed sugarcane which stores large amounts of sucrose, and S. spontaneum is thin-stemmed with very little sucrose. Sucrose synthase (SS), sucrose phosphate synthase (SPS), and invertase enzymes are thought to affect the accumulation of sucrose in the stems of sugarcane. This study was performed to determine if (i) differences between SPS and acid invertase activities account for the difference in sucrose content of sugarcane stems, and (ii) differences in SS activity influence sucrose concentration. The difference between SPS and acid invertase activities did not appear related to the low sucrose content in S. spontaneum. However, the …