Autonomic cardiovascular responses to hypercapnia in conscious rats: the roles of the chemo- and baroreceptors.

The role of the autonomic nervous system, the central and peripheral chemoreceptors, and the arterial baroreceptors was examined in the cardiovascular response to hypercapnia in conscious rats chronically instrumented for the measurement of arterial blood pressure (ABP), heart rate (HR), and renal sympathetic nerve activity (RSNA). Rats were exposed to hypercapnia (6% CO2), and the cardiovascular and autonomic nervous responses in intact and carotid chemo- and/or aortic denervated rats were compared. In intact and carotid chemo-denervated rats, hypercapnia induced significant increases in mean ABP (MABP) and RSNA, and a significant decrease in HR. The HR decrease was reversed by atropine and eliminated by bilateral aortic denervation, which procedure, however, did not affect the MABP or RSNA response. Bilateral carotid chemo-denervation did not affect the baroreflex control of HR, although this control was attenuated by aortic denervation. Hypercapnia did not affect baroreflex sensitivity in intact rats. These results suggest that hypercapnia induces an increase in MABP due to an activation of sympathetic nervous system via central chemoreceptors and a decrease in HR due to a secondary reflex activation of the parasympathetic nervous system via arterial baroreceptors in response to the rise in ABP. In addition, carotid chemoreceptors do not play a major role in the overall cardiovascular response to hypercapnia in conscious rats. The mechanism responsible for the parasympatho-excitation may also involve CO2 induced aortic chemoreceptor simulation.

Coronary artery bypass surgery by the transdiaphragmatic approach.

BACKGROUND: The transdiaphragmatic approach is useful for reoperative coronary artery bypass grafting involving the right coronary artery because it does not require median sternotomy or cardiopulmonary bypass. METHODS: Twenty-one patients underwent coronary artery bypass surgery by the transdiaphragmatic approach. The ratio of first operations to reoperations was 7:14. The cause of reoperation was occlusion of a saphenous vein graft in 4 patients, right gastroepiploic artery graft failure in 3 patients, and a new sclerotic lesion in the right coronary artery in 7 patients. When the radial artery or saphenous vein was used, grafting extended from the origin of the gastroduodenal artery to the right coronary artery. RESULTS: None of the patients died during surgery. The sites of anastomoses were as follows: right coronary artery in 11 patients, right posterior descending artery in 9 patients, and the atrioventricular node artery in 1 patient. The following types of grafts were used: right gastroepiploic artery in 17 patients, saphenous vein in 2 patients, and radial artery in 2 patients. CONCLUSIONS: When reoperative coronary surgery involving the right coronary artery is necessary, the transdiaphragmatic technique is effective because it does not damage patent grafts placed during the primary operation.

Coronary artery bypass via diaphragmatic approach with free graft.

To avoid injury to patent bypass grafts or myocardium during median sternotomy in coronary artery bypass graft reoperation, we performed modified minimally invasive direct coronary artery bypass to the right coronary artery via diaphragmatic approach using the right gastroepiproic artery. In cases in which the right gastroepiproic artery cannot be used, this technique is performed with a free graft from the gastroduodenal artery. This approach is very useful for reoperation in these circumstances.

Development of proximal calciphylaxis with penile involvement after parathyroidectomy in a patient on hemodialysis.

Elevated parathyroid hormone (PTH) levels and hyperphosphatemia are thought to be associated with the development of calciphylaxis. We report a patient on hemodialysis who developed proximal calciphylaxis with consistently low PTH levels after parathyroidectomy. A 31-year-old man was admitted to our hospital because of abdominal skin ulcerations. Calciphylaxis spread to the penis, and simultaneous progressive lung calcification was evident on chest X-ray, suggestive of pulmonary calciphylaxis on 99mTc-methylene disphosphonate scintigraphy. The patient died of respiratory failure despite intensive treatment including hyperbaric oxygen therapy. This is the first report of a patient on hemodialysis who developed calciphylaxis involving the penis after parathyroidectomy.

Coronary artery bypass grafting using an abdominal artery as an inflow.

BACKGROUND: In multiple bypass surgery, when the ascending aorta cannot be used as an inflow, it is sometimes necessary to use an abdominal artery. This technique is useful when a re-median sternotomy might damage a patent graft in patients undergoing reoperations or when the gastroepiploic artery is unsuitable for use as a graft. METHODS: The subjects were 17 patients in whom an abdominal artery was used as an inflow. In these 17 patients, 9 underwent surgery for the first operation, while 8 underwent surgery for the reoperation. As an inflow, the gastroduodenal artery was used in 8 patients, the common hepatic artery in 4 patients, the left gastric artery in 3 patients, the right gastric artery in 1 patient, and the middle colic artery in 1 patient. The target coronary artery was the right posterior descending artery in 13 patients, the atrioventricular artery in 2 patients, and the circumflex artery in 4 patients. Sequential bypass was performed on 2 patients. RESULTS: None of the patients died during surgery. Symptoms disappeared postoperatively in all patients; postoperative angiography showed that all grafts were patent. CONCLUSIONS: The present technique is useful when the ascending aorta cannot be used as an inflow or when a bypass to a region with a large perfusion area is needed in multiple bypass surgery.

Synergistic induction of monocyte chemoattractant protein-1 by integrins and platelet-derived growth factor via focal adhesion kinase in mesangial cells.

BACKGROUND: Growth factors, extracellular matrix and its receptor integrins are upregulated in various glomerular diseases. We investigated the mechanism of collaboration between integrins and platelet-derived growth factor (PDGF) in focal adhesion kinase (FAK)- and extracellular signal-related kinase (ERK)1/2-mediated signal pathways that lead to monocyte chemoattractant protein (MCP)-1 expression in cultured rat mesangial cells (MCs). METHODS: Serum-starved MCs were plated on fibronectin- or polylysine-coated plates with or without PDGF, and examined for phosphorylation of ERK1/2, mitogen-activated protein or ERK kinase (MEK)1/2 and FAK by western blotting, and for expression of MCP-1 mRNA and protein by reverse transcription-polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA), respectively. The effects of dominant-negative FAK on MCP-1 expression were examined. RESULTS: Cell adhesion to fibronectin increased phosphorylation of FAK, MEK1/2 and ERK1/2, and induced MCP-1 mRNA and protein expression. PDGF increased phosphorylation of FAK, MEK1/2 and ERK1/2 even without cell adhesion to fibronectin, and induced MCP-1 mRNA and protein expression. PDGF with integrin activation by fibronectin synergistically increased phosphorylation of FAK, MEK1/2 and ERK1/2, and expression of MCP-1 mRNA and protein. Dominant-negative FAK attenuated fibronectin enhancement of PDGF-induced ERK1/2 phosphorylation and MCP-1 expression, indicating involvement of FAK in this signalling. CONCLUSIONS: Our results suggest the cooperative role of integrin and PDGF receptor in activation of the ERK pathway possibly via FAK in MCs. The synergistic activation of integrin and PDGF signalling may play an important role in the progression of glomerular diseases through the induction of MCP-1.

Early and mid-term outcome of anastomosis of gastroepiploic artery to left coronary artery.

BACKGROUND: The performance of a bypass made to the left coronary artery using the gastroepiploic artery was examined. METHODS: Sixty-nine cases of bypass operation in which the gastroepiploic artery had been anastomosed to the left coronary artery at least 3 years prior were examined. All cases were performed by the same surgeon during the period from April 1989 to April 2000. Performance immediately after the operation and performance at least 3 years after the operation were examined on the basis of graft patency rate. RESULTS: Graft patency rates in cases with an anastomosis to the left anterior descending coronary artery and cases with an anastomosis to the circumflex artery were favorable immediately after the operation, at 96.0% (24 of 25) and 100% (18 of 18), respectively. However, over the mid-term, the patency rate dropped to 58.8% (10 of 17) in cases with an anastomosis to the left anterior descending artery, and two cases of cardiogenic sudden deaths occurred during the course of follow-up. The graft patency rate in cases with an anastomosis to the circumflex artery, on the other hand, remained favorable, at 93.3% (14 of 15). In a sequential bypass grafting through the right coronary artery, the graft between the left anterior descending coronary artery and the right coronary artery was closed, and the graft patency rate between the right coronary artery and the circumflex artery was 71.4% (10 of 14). CONCLUSIONS: The mid-term patency rate was poor for cases in which the gastroepiploic artery had been anastomosed to the left anterior descending coronary artery, which suggests that the procedure should be avoided. On the other hand, the patency rate was relatively favorable when the gastroepiploic artery had been anastomosed to the circumflex artery.