PubMed Health⌕ Search

Biomedical subjects

F W Beck

Publications and source records attributed to F W Beck.

58 records · Page 4Linked to original sources
PubMedDate not supplied

Catecholamine, renin, aldosterone, and arginine vasopressin responses to lower body negative pressure and tilt in normal humans: effects of bromocriptine.

We have examined the effects of the dopamine agonist bromocriptine (BEC) on the hormonal and hemodynamic response to graded lower body negative pressure (LBNP) and tilting in five normal volunteers. BEC blunted the plasma norepinephrine (NE), plasma renin activity (PRA), and aldosterone responses to both LBNP and tilting. The inhibitory effects of BEC on the plasma NE response to these maneuvers are likely mediated through presynaptic inhibition of peripheral neuronal release of NE as well as central nervous system effects of the drug. Since the PRA responses to LBNP and tilting are likely mediated through beta-adrenoreceptor stimulation, BEC probably indirectly blunts the PRA and aldosterone responses to those maneuvers through its inhibitory effects on NE secretion. BEC treatment resulted in a hypotensive response to tilting that was accompanied by a rise in plasma potassium and arginine vasopressin (AVP). No such rises in plasma potassium and AVP are observed, in the absence of BEC treatment, following graded LBNP and tilting. The rise in plasma potassium with tilting (BEC treatment) probably resulted from blunting of the NE rise. Thus, the rise in plasma NE may play an important role in preventing a rise in plasma potassium in association with LBNP and orthostatic stress. AVP levels in normal men are not responsive to unloading of cardiopulmonary and sinoaortic baroreceptors. It is only after overt hypotension is produced--as after BEC treatment--that plasma levels of AVP rise.

Adult↗
PubMedDate not supplied

Effects of high calcium intake on blood pressure and calcium metabolism in young SHR.

Increased dietary calcium intake in the adult spontaneously hypertensive rat (SHR) has been reported to correct low serum ionized calcium concentration ([Ca++]) and to result in a significant amelioration of the prevailing hypertension. In the present study we examined several parameters of calcium metabolism in young (6-week-old) SHR and compared them with those observed in normotensive Wistar-Kyoto (WKY) rats fed equal amounts of a diet containing normal quantities of calcium (0.4%, wt/wt) for 4 weeks. A separate group of SHR was placed on an equal amount of a high calcium (2.8%, wt/wt) but otherwise identical diet. In SHR and WKY eating a normal calcium diet, serum total calcium concentration was not different, but [Ca++] was lower in SHR (1.58 +/- 0.06 vs 1.91 +/- 0.07 mmol/liter, p less than 0.01). Serum immunoreactive parathyroid hormone (PTH) was increased in some, but not all, SHR. No difference was noted between the two groups in the following parameters: calcium intake, serum 1,25 dihydroxycholecalciferol (1,25(OH)2D3), urinary calcium excretion, fractional stool calcium content ([stool calcium/calcium intake] X 100), and in vitro 45Ca uptake by everted gut sacs constructed from segments of duodenum, mid-jejunum, ileum, and proximal colon. A high calcium diet corrected the abnormal serum [Ca++] and PTH but did not alter the progression or severity of the hypertension in SHR. A lower net weight gain was observed in SHR on a high calcium diet when compared to SHR eating normal calcium diet (9.1 +/- 1.8 vs 27.0 +/- 2.0 g).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗