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Jos F M Smits

Publications and source records attributed to Jos F M Smits.

6 recordsLinked to original sources
PubMed2002

Deficiency of TIMP-1 exacerbates LV remodeling after myocardial infarction in mice.

Recent studies have been directed at modulating the heart failure process through inhibition of activated matrix metalloproteinases (MMPs). We hypothesized that a loss of MMP inhibitory control by tissue inhibitor of MMP (TIMP)-1 deficiency alters the course of postinfarction chamber remodeling and induced chronic myocardial infarction (MI) in wild-type (WT) and TIMP-1(-/-) mice. Left ventricular (LV) pressure-volume loops obtained from WT and TIMP-1(-/-) mice demonstrated that LV end-diastolic volume [52 +/- 4 (WT) vs. 71 +/- 6 (TIMP-1(-/-)) microl] and LV end-diastolic pressure [9.0 +/- 1.2 (WT) vs. 12.7 +/- 1.4 (TIMP-1(-/-)) mmHg] were significantly increased in the TIMP-1(-/-) mice 2 wk after MI. LV contractility was reduced to a similar degree in the WT and TIMP-1(-/-) groups after MI, as indicated by a significant fall in the LV end-systolic pressure-volume relationship. Ventricular weight and cross-sectional areas of LV myocytes were significantly increased in TIMP-1(-/-) mice, indicating that the hypertrophic response was more pronounced. The observed significant loss of fibrillar collagen in the TIMP-1(-/-) controls may have been an important contributory factor for the observed LV alterations in the TIMP-1(-/-) mice after MI. These findings demonstrate that TIMP-1 deficiency amplifies adverse LV remodeling after MI in mice and emphasizes the importance of local endogenous control of cardiac MMP activity by TIMP-1.

Animals↗
PubMed2002

The role of locally expressed angiotensin converting enzyme in cardiac remodeling after myocardial infarction in mice.

OBJECTIVE: Angiotensin II, generated from angiotensin I by angiotensin converting enzyme (ACE), induces multiple effects including vasoconstriction, positive cardiac inotropy, hypertrophy of cardiomyocytes and proliferation of fibroblasts. ACE exists both in a tissue-bound (t-ACE) and a soluble form. The functional importance of locally produced angiotensin II is still unclear. In the present study, mice lacking tissue-bound angiotensin converting enzyme (t-ACE -/-) were used to investigate the importance of t-ACE during cardiac remodeling after myocardial infarction. METHODS: Mice were subjected to coronary artery occlusion or sham surgery. At 14 days after MI, stroke volume (SV) was determined with an electromagnetic flow probe around the ascending aorta. Mean arterial pressure (MAP) was measured through a cannula in the abdominal aorta. Both parameters were determined at rest and after a volume loading of 2.5 ml warm (37 degrees C) Ringer's solution in 60 s. Hearts were dissected and formalin-fixed to measure infarct size, cardiac dimensions and collagen concentration. Tissue levels of angiotensin I and II were determined in hearts and kidneys. RESULTS: At rest, under pentobarbital anaesthesia, t-ACE -/- mice (n=12) exhibited a significantly lower MAP (26+/-3 vs. 45+/-3 mmHg) than t-ACE +/+ (n=11). SV was similar in both strains. Maximal SV was significantly reduced after MI. Furthermore, infarcted t-ACE -/- (n=6) exhibited a significantly lower maximal SV compared to infarcted t-ACE +/+ mice (n=5; 20.4+/-1.5 vs. 29.6+/-2.3 microl). Structural cardiac parameters as well as cardiac and renal angiotensin II levels in t-ACE -/- and t-ACE +/+ were comparable. CONCLUSIONS: These results suggest that the structural adaptations of the heart that follow MI are independent of t-ACE. However, the presence of t-ACE is necessary for maintenance of cardiac function.

Angiotensin I↗
PubMed2002

Pharmacokinetic advantage of intrapericardially applied substances in the rat.

Intrapericardial application of therapeutic agents may open perspectives for target-directed therapy of the diseased heart. This study was performed to investigate whether intrapericardial drug application is beneficial from a pharmacokinetic point of view. Male Wistar rats were provided with intrapericardial and intravascular catheters for substance administration and sampling. Intrapericardial bolus injections of fluorescent macromolecules [fluorescein isothiocyanate (FITC)-rat IgG, molecular weight about 155 kDa; Texas Red rat serum albumin, mol. wt. 67 kDa; Texas Red fibroblast growth factor (FGF), mol. wt. 18 kDa; and FITC heparin, mean mol. wt. 18 kDa] resulted in substance concentrations in pericardial fluid that exceeded those in plasma, for several hours. Pericardial fluid volumes of catheter-instrumented rats, derived from (initial) central compartment volumes, ranged between 0.5 and 0.9 ml/kg. After chronic (7 days) intrapericardial infusions with osmotic minipumps, pericardial fluid/plasma concentration ratios (local advantages) were 7 to 10 for the fluorescent proteins and >30 for FITC-heparin. This can be explained by the low substance clearances in pericardial fluid compared with plasma. Local advantages of the small substances cortisol (mol. wt. = 362.5) and a carbonic acid derivative thereof (mol. wt. = 348) were 14 and 420. Intrapericardial infusion of (125)I-FGF-2 yielded 8 times higher cardiac tissue levels than systemic infusion, whereas (125)I-FGF-2 was found in the entire heart. Pharmacokinetic profiles of intrapericardially applied substances are such that desired local drug concentrations can be obtained at lower dosages, whereas systemic concentrations remain low (thus reducing the potential risk of peripheral side effects). Therefore, intrapericardial application of therapeutic agents provides a promising strategy for site-specific treatment of heart or coronary diseases.

Animals↗
PubMed2002

Autonomic control of blood pressure in mice: basic physiology and effects of genetic modification.

Control of blood pressure and of blood flow is essential for maintenance of homeostasis. The hemodynamic state is adjusted by intrinsic, neural, and hormonal mechanisms to optimize adaptation to internal and environmental challenges. In the last decade, many studies showed that modification of the mouse genome may alter the capacity of cardiovascular control systems to respond to homeostatic challenges or even bring about a permanent pathophysiological state. This review discusses the progress that has been made in understanding of autonomic cardiovascular control mechanisms from studies in genetically modified mice. First, from a physiological perspective, we describe how basic hemodynamic function can be measured in conscious conditions in mice. Second, we focus on the integrative role of autonomic nerves in control of blood pressure in the mouse, and finally, we depict the opportunities and insights provided by genetic modification in this area.

Animals↗