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Biomedical subjects

P T Jokelainen

Publications and source records attributed to P T Jokelainen.

At least 19 recordsLinked to original sources
PubMed1989

Blood pressure and acidic renin forms in stroke-prone hypertensive rats.

Six forms of renin, distinguishable by their isoelectric focusing characteristics, are found in rat kidney and plasma (forms 1-6, form 1 having the most basic pI). To test the hypothesis that high blood pressure in stroke-prone spontaneously hypertensive rats (SHRSP) is associated with a particular fraction of the renin forms, systolic blood pressure (SBP) and renin profile were measured in SHRSP, normotensive Wistar-Kyoto rats (WKY), and their genetic crosses (F1). Adult SHRSP showed an increase in the proportion of forms 4, 5, and 6 compared with WKY. F1 showed values between SHRSP and WKY. A strong positive correlation was noted between the fraction of the acidic forms of renin and SBP. The mean blood pressure and the fraction of the acidic renin forms in SHRSP and WKY pups also fitted the same regression line. However, no correlation existed between renal renin content (RRC) and SBP. SHRSP pups had a higher RRC than age-matched WKY or F1. RRC in normal adult SHRSP was lower than that in WKY or F1 of the same age. In old animals, SHRSP again showed the highest RRC, and microangiography of the kidney of old SHRSP revealed a loss of fine vascularity with few visible glomeruli. These results indicate that the established phase of hypertension in SHRSP is associated with an increased proportion of the acidic forms of renin, which may have a unique role in the establishment or maintenance of hypertension. It is also suggested that high RRC in the early developmental stage plays a role in the developing phase of hypertension.

Aging↗
PubMed1987

Genetic relationship between a lymphocyte membrane abnormality and blood pressure in spontaneously hypertensive stroke prone and Wistar-Kyoto rats.

The fluxes of sodium and potassium across the lymphocyte membrane in spontaneously hypertensive, stroke prone rats (SHRSP) are greater than those in Wistar-Kyoto rats (WKY). In order to define the relationship of these abnormal membrane traits to arterial pressure elevation, their distributions were studied in F1, F2, and backcross progeny of the cross of SHRSP and WKY rats. In the F1 generation, arterial pressure and potassium efflux values resembled those of the WKY parents suggesting that these traits are dominant in the normotensive rat; sodium influx values resembled those of the SHRSP parents. There was poor correlation (r = 0.45) between blood pressure and sodium influx in the F2 generation. There was a high correlation between blood pressure and potassium efflux (r = 0.86), suggesting that these two traits may be under the control of a common genetic mechanism.

Animals↗
PubMed1986

Renin heterogeneity in stroke-prone hypertensive and normotensive rats.

Six forms of renin are found in the rat kidney. We studied their secretion in renal slices from spontaneously hypertensive stroke-prone rats (SHRSP) and Wistar-Kyoto rats (WKY). Incubation media from renal slices were subjected to isoelectric focusing. Six peaks of renin activity with different isoelectric points were found. The renin concentration of each form was expressed as a percentage of the total recovered from the gel. We established that the forms secreted by renal slices of SHRSP differed from those of WKY: SHRSP slices released a higher proportion of forms focusing at the more acidic pH. The distribution of the six renin forms and of blood pressure (BP) among animals of the F1, F2, and backcross progenies resulting from the cross of SHRSP and WKY rats were studied. In the F1, BP, percentage of renin form 2, and a combination of the percentage of forms 4 + 5 + 6 were intermediate between the parental lines. The backcross rats showed BP and percentages of forms closer to their SHRSP or WKY parent. In the F2, the distribution of BP, percentage of forms 2 and 4 + 5 + 6 take the form of a unimodal distribution with a significantly larger variance than F1. The increase in the correlation between percentage of renin forms and BP, and between renin concentration of BP, in the segregating progenies over that observed in the parental lines and the F1, are support for the hypothesis that these traits are under the control of common genetic mechanisms.

Animals↗
PubMed1986

Genetic basis for altered vascular responses to ouabain and potassium-free solution in hypertension.

Many properties intrinsic to vascular smooth muscle are altered in hypertension. It is unknown whether these abnormalities are primary traits that may contribute to the etiology of hypertension or whether these vascular differences between the hypertensive and normotensive strains are inherited independently of genetic factors that predispose to hypertension. To determine if genetic factors responsible for the predisposition for hypertension may be the same as or linked to genetic factors determining a specific vascular response, adult stroke-prone spontaneously hypertensive rats (SHRSP), normotensive Wistar-Kyoto (WKY) rats, and progeny of genetic crosses of SHRSP and WKY rats (F1, F2, F1 X WKY, F1 X SHRSP) were studied. Rats were killed and helical aortic strips were mounted in a tissue bath for isometric force recording. Contractile responses to 10(-3) M ouabain (expressed as a percent of force generated to a maximal depolarizing stimulus) were greater in aortas from SHRSP (90 +/- 9%) compared with aortas from WKY rats (38 +/- 5%, P less than 0.05). The half time for contraction in K+-free solution was more rapid in aortas from SHRSP (21 +/- 4 min) when compared with aortas from WKY rats (48 +/- 4 min, P less than 0.05). A significant positive correlation between blood pressure (tail-cuff method) and the contractile response to 10(-3) M ouabain was observed in the segregating F2 progeny. In contrast, no correlation between blood pressure and the half time for contraction in K+-free solution was observed in the segregating F2 progeny.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Genetic association of hypertension and vascular changes in stroke-prone spontaneously hypertensive rats.

Isolated tail arteries from stroke-prone spontaneously hypertensive rats (SHRSP) exhibit oscillatory contractile activity in response to norepinephrine, whereas those from normotensive Wistar-Kyoto rats (WKY) do not. To determine whether the norepinephrine-induced oscillations are related to high blood pressure or to separable genetic differences between strains, the response to norepinephrine was studied in adult SHRSP, WKY, and progeny of genetic crosses of SHRSP and WKY (F1, F2, F1 X SHRSP, F1 X WKY). Helical tail artery strips were mounted in a tissue bath for isometric force recording. Rats were classified as responders if oscillatory activity in the presence of 1.8 X 10(-7) M norepinephrine exceeded 250 mg/10 min (milligrams of force amplitude during a 10-minute interval). The blood pressures (mm Hg +/- SEM; tail cuff method) and percentage of rats exhibiting norepinephrine-induced oscillations were as follows: WKY: 109 +/- 3, 0%; F1: 129 +/- 4, 0%; F2: 150 +/- 4, 38%; F1 X WKY: 137 +/- 3, 9%; F1 X SHRSP: 188 +/- 7, 71%; SHRSP: 207 +/- 7, 100%. The distribution of the frequency of animals with oscillatory activity among the progenies was consistent with the hypothesis that a single gene locus determines the observed difference in oscillatory activity between the WKY and SHRSP strains. The allele from the SHRSP that determines the activity phenotype is recessive to the allele contributed by the normotensive WKY strain. In the segregating F2 progeny, the blood pressure of the responders was higher than that of the nonresponders (161 +/- 6 vs 144 +/- 4 mm Hg; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Alleles↗
PubMed1982

Dorsal cerebral arterial collaterals of the rat.

This study demonstrated that distal branches of the anterior cerebral artery (ACA) are joined by interarterial anastomoses to rami of the middle cerebral artery (MCA) in the normal Wistar rat. Arteries of 36- and 56-day-old animals were dilated with papaverine and injected with Vultex. Vultex arrived at corresponding ACA and MCA collaterals simultaneously as determined by microscopy through a skull window and photography. There were about 29 ACA-MCA junctions per hemisphere. Junction density was nearly constant along the frontal-occipital axis. The anastomoses were most numerous between 2 and 3 mm lateral to the midline and were less than 120 micron in internal diameter. No significant difference was found between total numbers of junctions for right versus left hemispheres or between age groups. The most evident collateral pattern was characterized by two ACA end rami joining two MCA end branches to form a closed, diamond-shaped collateral unit. Considerations were given to alternate routes of blood flow into the MCA tissue field. We conclude abundant dorsal anastomoses exist in 36- and 56-day-old rats and are the prime potential source for ACA collateral supply to the MCA tissue field.

Age Factors↗
PubMed1976

Lamellated osmiophilic bodies in mouse gallbladder epithelium.

Mouse gallbladder epithelium was studied in the electron microscope after glutaraldehyde and osmium tetroxide fixation and Epon embedding. Special attention was paid to dense cytoplasmic bodies. Heterogeneous dense bodies with osmiophilic and loose granular components were identified. Many of these bodies consisted of lamellated osmiophilic structures, similar to the phospholipid bodies of the large alveolar (type II) cells of the mammalian lung. The dense bodies containing the lamellar structures were membrane-limited and 0.5-1.0 mum in diameter. They were located in the supranuclear cytoplasma and were often closely associated with the Golgi apparatus. Acid phosphatase activity was demonstrated within these bodies and in some of the Golgi vacuoles. The contents were disposed in concentric lamellar osmiophilic structures, sometimes appearing as scroll-like configurations. These morphological findings were interpreted as indication of these presence of phosphlipid absorbed from the gallbladder lumen and stored in phagosomes in the central cytoplasm of the gallbladder epithelial cells.

Acid Phosphatase↗