Blood Flow In Goats Research Articles

Passive immunization against inhibin increases testicular blood flow in male goats

The present study investigated whether or not passive immunization against inhibin modulates testicular blood flow in goats. Male Shiba goats were injected with either 10 ml of inhibin antiserum (INH group; n = 5) or 10 ml of normal castrated goat serum (NGS group; n = 4). Concentrations of FSH, LH, testosterone (T), and estradiol (E2) in the plasma were measured by radioimmunoassay. Blood flow within the supratesticular (STA) and marginal testicular arteries (MTA) were measured by color pulsed-Doppler ultrasonography, and Doppler indices (resistive index; RI and pulsatility index; PI) were recorded. Results revealed significant increases in concentrations of FSH and E2 in the INH group compared to those in the NGS group (P < 0.05). Animals in the INH group had greater (P < 0.05) FSH concentrations than those in the NGS group in the period between 60 h and 144 h after treatment than at any other time. Estradiol concentrations were greater (P < 0.05) in the INH group than in the NGS group at 6 h (12.15 ± 2.09 pg/ml vs 5.49 ± 1.17 pg/mL), 12 h (8.27 ± 1.29 pg/mL vs 3.05 ± 0.38 pg/mL), and 36 h (9.35 ± 1.31 pg/mL vs 5.09 ± 0.46 pg/mL) after treatment than at any other time. Concentrations of LH and T did not significantly change between the two groups. Goats in the INH group had lesser (P < 0.05) RI of the STA than those in the NGS group and RI values were lesser at 24 h (0.37 ± 0.031 vs 0.49 ± 0.004) and 120 h (0.38 ± 0.028 vs 0.55 ± 0.048) after treatment than at any other time. Furthermore, values of RI and PI of the MTA were significantly lesser (P < 0.05) in the INH group compared to those in the control group at 48 h (RI of MTA: 0.21 ± 0.014 vs 0.37 ± 0.039; PI of MTA: 0.24 ± 0.016 vs 0.46 ± 0.058) after treatment than at any other time. In conclusion, passive immunization against inhibin has a stimulatory effect on testicular blood flow in goats by inducing decreases in the RI values of the STA and MTA.

Insulin-like growth factors in milk and mammary gland.

Milk contains insulin-like growth factor I and II (IGF-I and IGF-II) and four IGF binding proteins (IGFBP). Their concentrations are highest prepartum and early postpartum, coinciding with maximal proliferation of mammary cells and the time when the infant gut is the least developed. This has lead to the suggestion that IGFs may be important for the growth and development of the mammary gland and that IGFs in milk play a role in promoting development of the gastrointestinal tract of the newborn. IGF-I and, to a lesser extent, IGF-II can stimulate milk yield and blood flow in goats when infused directly into the mammary gland, suggesting they may also be important in supporting established lactation. Thus IGFs may have a dual function in the mammary gland, establishing and maintaining the maternal mammary system and, once secreted into milk, supporting gastrointestinal development in the newborn.

Evaluation of mammary blood flow measurements in lactating goats using the ultrasound doppler principle

1. 1. Non-invasive methods were developed for measuring mammary blood flow in lactating goats. 2. 2. A Doppler principle ultrasound device was equipped with an external detector measuring maximal blood velocity ( V max) and average blood velocity ( V av) was calculated as V max/2. Volume now then depended on determination of the angle of insonation and the cross-sectional area of the milk vein (the caudal superficial epigastric or subcutaneous abdominal vein). 3. 3. Blood velocities were measured on the milk vein of either side of the animal while clamping the pudendal veins manually. Blood velocities ranged from 7–34 cm/sec. 4. 4. The milk vein diameter was measured by means of a slide gauge which, for clearly protruding veins, gave similar results to that measured by ultrasound scanning. In protruding veins the cross-section was circular. In non-protruding veins the cross-section was elliptical and the slide gauge significantly ( P < 0.01) overestimated the cross-sectional area. The milk vein diameter of either side measured in 10 lactating goats was 8.8 ± 1.1 mm ( x ± SD). 5. 5. Blood flow ranged from 90–675 ml/min in a dry and a high-yielding (3.41 milk daily) goat, respectively. The reproducibility of the blood flow measurements was 12–16%. 6. 6. It is concluded that the present method may be used for quantitative measurements of mammary blood flow in goats.

Effects of body surface thermal injury on apparent renal and cutaneous blood flow in goats.

The etiology of postburn circulatory impairment ("burn shock") is multifactorial and incompletely understood. However, systemic vasoconstriction is a consistent observation during this period and occurs in spite of aggressive fluid resuscitation therapy. We studied the degree and time course of systemic vasoconstriction in goats for 24 hours following burns of two sizes (20% and 35% TBSA), in which fluid resuscitation was performed according to a common clinical crystalloid regimen. Cardiac index and urine output (reflecting renal perfusion) fell dramatically at two hours after burn, but returned slowly to preburn levels by 24 hours. The degree of fall and rate of recovery were dependent on burn size. Dermal perfusion was assessed by laser Doppler flowmetry in both burned and unburned skin. Dermal perfusion was negligible in burned skin. Unburned skin blood flow fell with increasing burn size, progressively recovered to preburn levels after the small burn, but at 24 hours remained significantly depressed after the larger burn. The stimulus for this persistent skin vasoconstriction is unclear.

Vasoactive intestinal polypeptide and endometrial blood flow in the goat

Endometrial blood flow was measured in seven goats twice before, once during, and twice after the close intra-arterial infusion of 300 pmol/min of vasoactive intestinal polypeptide (VIP). A saline solution of 85krypton was injected intra-arterially and local blood flow calculated from the disappearance rate of the isotope from tissue surrounding a miniature Geiger-Müller probe in the uterine lumen. Initial blood flows (median and range) in animals pretreated with oestradiol-17β ( N = 4) or with a regimen of oestradiol-17β and progesterone ( N = 3), respectively, were 0.21 (0.11–0.35) and 0.20 (0.06–0.27) ml min −1 g −1. No significant change in endometrial blood flow occurred during or after the infusion of VIP, although the dose was sufficient to increase heart rate from 2.14 ± 0.15 to 2.32 ± 0.16 Hz ( P < 0.001). The results indicate that VIP, in a dose known to increase myometrial blood flow in goats, is unable to evoke vasodilatation in the endometrium of this species. Since there is a corresponding variation in the density of nerve fibers containing VIP, it is suggested that VIP may play a role in regulating the partition of uterine blood flow in goats.