| dc.contributor.author | Gamperl, Anthony Kurt. | en_US |
| dc.date.accessioned | 2014-10-21T12:33:30Z | |
| dc.date.available | 1994 | |
| dc.date.issued | 1994 | en_US |
| dc.identifier.other | AAINN93772 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55408 | |
| dc.description | In fish, the adrenergically-mediated stimulation of cardiac performance is an important physiological response to stress. However, few studies have evaluated the in vivo dose-response relationship for cardiovascular variables at physiological catecholamine (CA) levels, and no studies have evaluated whether repeated CA exposure reduces cardiac adrenergic sensitivity. In addition, information is lacking on how coronary flow (CF) and adrenergic stimulation interact to determine in vivo cardiac performance. | en_US |
| dc.description | The ED$\sb{50}$ values for epinephrine-stimulated cardiac output (Q) and dorsal aortic pressure (P$\sb{\rm DA}$) were 0.22 $\mu$g kg$\sp{-1}$ and 0.48 $\mu$g kg$\sp{-1}$, respectively, with Q approaching a maximum at the highest dose (2.0 $\mu$g kg$\sp{-1}$). Removal of the coronary artery had no effect on cardiac performance at any epinephrine dose. These results suggest that small increases in plasma CA levels can cause large increases in Q, and that O$\sb2$ delivery from the luminal blood to the myocardium is not limited during normoxia. Measurements of Q, P$\sb{\rm DA}$, and CF during hypoxia and following epinephrine injection revealed that increases in CF are important for determining Q during hypoxia, and that vasoconstriction of the coronary artery may limit cardiac performance during hypoxic conditions. | en_US |
| dc.description | Using a new micropunch technique, it was found that cell-surface $\beta$-receptors in the trout ventricle represent a single population of $\beta\sb2$-type receptors with a K$\sb{\rm d}$ of 0.25 nM and a density of 12,000 sites per cell. The repeated injection of CAs did not alter ventricular $\beta$-receptor density or K$\sb{\rm d}$. Neither acute nor chronic injection of epinephrine affected CA clearance and metabolism. The CA clearance/metabolism and $\beta$-receptor experiments indicate that the duration and/or the magnitude of CA-stimulated cardiovascular effects are unlikely to be altered by previous CA exposure. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 1994. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Animal Physiology. | en_US |
| dc.subject | Agriculture, Fisheries and Aquaculture. | en_US |
| dc.title | Influence of adrenergic stimulation and coronary blood flow on in vivo cardiac performance in rainbow trout (Oncorhynchus mykiss). | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
